N55 No Low Fuel Pressure Sensor??? HELP!!!

kenlena46 · 01-21-2020, 08:52 AM

I need some help here and need to pick all your brains. My 2011 535i N55 had a check engine light come on so I took it to the mechanic to see what was going on. He said the coolant temperature sensor isn’t working correctly and he thinks I need a new sensor or it has some sort of electrical problem/short going on. He also said the car is giving a code for the low fuel pressure sensor so he advised me to take it to the BMW dealer to have them go through it because he thought it had to do with an electrical problem.

I took it into the dealership and they said the coolant temperature sensor was bad and needed to be replaced and the low fuel pressure sensor was bad and needed to be replaced as well. Because they wanted to charge me over $800 to do the job I decided it all looked fairly easy and I could do it myself. I got the parts from BMW and went to do the work. I noticed as I was looking for the low fuel pressure sensor that it was nowhere to be found. I did some research and found out that my vehicle wasn’t produced with a low fuel pressure sensor (N55 motor). So I went back to BMW and told them what I found and asked for them to find the reason my vehicle was putting out this code if the vehicle was made without that sensor. They ended up telling me that they have no clue why it does not have the low fuel pressure sensor and that they think I had my motor swapped at some point and during that process they deleted the sensor which is all BS! I asked them to provide me with pictures of the different vin number they found on the engine and they wouldn’t provide me with them.

So their solution to the problem was we can take the vehicle in on trade and give you a great deal on a new BMW and that’s all they could do.

I’m just looking to see if anyone else has experienced this whole no low fuel pressure sensor thing???

95blkmax · 01-22-2020, 08:31 AM

you HAVE to have a low pressure sensor. It's the only way the DME knows that your LPFP is working within operating range. It's on the fuel line feeding the HPFP. See this diagram from realoem (SEE ITEM #7)

https://www.realoem.com/bmw/enUS/sho...diagId=13_1355.

The coolant temp sensor IS the one you have pictures on the side of the block under the IM.

You're almost there buddy you got this!

mfractal · 01-24-2020, 03:40 AM

Quote:

Originally Posted by 95blkmax

you HAVE to have a low pressure sensor. It's the only way the DME knows that your LPFP is working within operating range. It's on the fuel line feeding the HPFP. See this diagram from realoem (SEE ITEM #7)

https://www.realoem.com/bmw/enUS/showparts?id=FR73-USA-04-2011-F10-BMW-535i&diagId=13_1355.

The coolant temp sensor IS the one you have pictures on the side of the block under the IM.

You're almost there buddy you got this!

There are indeed cars without the low pressure sensor. You can even see the alternative pipe without the sensor fitting on it below the one with sensor number 7. I've seen it myself on a few x5 and x6 here

95blkmax · 01-24-2020, 11:21 AM

Quote:

Originally Posted by mfractal

There are indeed cars without the low pressure sensor. You can even see the alternative pipe without the sensor fitting on it below the one with sensor number 7. I've seen it myself on a few x5 and x6 here

Interesting! Thanks for the enlightenment. So with the possibility of him not actually having a fuel low press sensor, and getting a code for low fuel press sensor... would this then imply a problem at the in tank pump? Since the HPFP has its own sensor... What think you?

mfractal · 01-25-2020, 05:28 AM

Quote:

Originally Posted by 95blkmax

Interesting! Thanks for the enlightenment. So with the possibility of him not actually having a fuel low press sensor, and getting a code for low fuel press sensor... would this then imply a problem at the in tank pump? Since the HPFP has its own sensor... What think you?

To be honest i am not sure the code he got is for low pressure side.
I'd love to see the code myself. Is it possible OP ?

ZeBoost · 01-07-2021, 10:37 PM

Hello All,

My, my it's a small world after all. I believe I purchased the vehicle that OP posted about! I was Googling for a solution to this odd error code and came across this post.

When I purchased the car from OP, it needed an alternator. I purchased an OEM alternator (Bosch) as I couldn't find the original Denso. After the swap, the car fired up (long crank) and ran rough (random misfires) but alternator was indeed charging the system. After a few short drives, the car went into an odd limp mode. The iDrive went dark, the instrument cluster looked like an Xmas tree and the car had about 5% power. I just managed to get it off to the side of the road. I turned it off, then back on and it fired back up (still long crank, still misfiring) and got me home. I checked the codes and there were multiple modules listing over voltage messages. Long story short, I purchased an alternator direct from BMW and installed it and that took care of the over voltage issues (still long cranks, still misfires).

The pics that OP posted are accurate, the car indeed does not have a LP sensor, at least not where it should be. The HPFP supply line has a hex shaped knob with no way to install a sensor.

This brings us to my current dilemma, the car is still long cranking and still misfiring at idle and is throwing a LP sensor code: 119202 FUEL LOW PRESSURE SENSOR, ELECTRICAL: SHORT TO GROUND

My next step will be to determine where this phantom sensor plugs into the DME and confirm whether or not, there are wires there and if they are shorted to ground. But if anyone on the forum can provide some insight into this code, I would greatly appreciate it.

For those wondering, HPFP looks good at the rail. I've logged crank, idle and light + medium loads. It has new BMW Bosch plugs and coils. Also, via the rail sensor I can confirm that the car shows a good LPFP before it cranks. An interesting bit of info, the car does show a LP sensor reading that stays pinned. No idea where that reading comes from (DME default possible).

Thanks everyone!

PS. An interesting development, when the car is in Sport or Sport +, 80% of the rough idle disappears.

AZ-MCRacer · 01-07-2021, 10:47 PM

I don't think any of the N55's have a LPFP pressure sensor.

ZeBoost · 01-08-2021, 02:17 AM

The strange part is that this car doesn’t but the DME thinks it does and it’s shorted.

ZeBoost · 01-23-2021, 12:49 AM

Hello All,

Just to keep those who've responded and those who may be curious about the vehicle updated, I was able to run diagnostics through INPA and the HPFP appears to be the issue. Fuel pressure at crank takes too long to build and at idle it fluctuates enough to potentially be the cause of my misfires. When the car is at higher RPMs the pump is able to keep up, which is why I don't feel the misfires anywhere but idle. This more than likely points to seal degradation inside of the HPFP. I've ordered a new HPFP, misc gaskets and a new HP sensor from ECS as part of a kit they offer. I should have the parts installed in the next 1-2 weeks and will report back then.

But the shadow code for the LP fuel sensor short (when the car doesn't have a LP fuel sensor) is still a mystery. I have verified with my own eyes that the car does not have a LPFS, at least were it's supposed to be.

TO BE CONTINUED...

ZeBoost · 02-04-2021, 04:11 PM

A quick update for those interested and those who may stumble on this thread, I received the HPFP kit from ECS yesterday and will be installing this weekend. Once it's in, I'll report back.

ZeBoost · 02-16-2021, 07:39 PM

An update for anyone who may stumble on this thread: after swapping out the HPFP and HP fuel sensor, the long crank is now resolved. The car fires up in about half a second every time; cold, hot, sitting for a while, turn off and back on, etc. It doesn't matter, the car fires right up every single time. But the intermittent miss at idle is still there. I used new gaskets and was careful putting everything back together again. The carbon build up at the valves didn't look too bad. I'm now suspecting I have a vacuum leak as the car runs strong everywhere in the rev range, doesn't smell rich or foul plugs (no CEL or shadow codes related to misfire, fuel, ignition, etc.). The next step will be a smoke test to see if I can find a leak.

F10_User · 07-01-2021, 11:51 AM

https://static.nhtsa.gov/odi/tsbs/20...46992-9999.pdf
recall on some vehicles.

ZeBoost · 07-01-2021, 12:13 PM

Thank you very much for sharing this! I did perform a smoke test and found no leaks under the hood but the slight miss is still there. I have two more items I am going to check: 1. An internal vacuum leak at the valve cover vacuum reservoir and 2. O2 sensor voltages, response time.

But I am now going to have another look for possible issues at the NVLD.

Ryanlocc · 08-13-2021, 11:11 PM

[QUOTE=ZeBoost;27095791]Hello All,
.

The pics that OP posted are accurate, the car indeed does not have a LP sensor, at least not where it should be. The HPFP supply line has a hex shaped knob with no way to install a sensor.

This is very interesting I have heard of this before though. I saw a few guys tslking about it on another forum one of them said that he was tired of it showing the code and another brought up that there are some N55s out there without that LPFP and that with that engine he wouldn't have a problem and now i this thread. But it weird because you say its not there yet it throws a code it makes me wonder what the problem is. My bmw threw the same code but ay the end it said short circuit to B+ which BMW said IS the sensor. Im guessing your problem is that its shorting out at the ground and that your cable has became ungrounded. I will ask my friend at BMW tmrw and report back but this is a curious one. The no LPFP N55 unicorn exists.

Let em know.

ZeBoost · 08-14-2021, 12:25 AM

By the way, the car still shows this code. Someone a few posts up mentioned an issue that could be possible due to the low pressure fuel pump. The car runs great but I still cannot figure out this code. A local indi mechanic even suggested the car could've had an ECU or engine swap at some point!

If I ever sort this out, I'll come back to clean out this thread. I still have a few things to do on the car but overall it runs well enough to be my daily so it's not a priority but still on the very long list of things to do.

Ryanlocc · 08-24-2021, 05:20 AM

Quote:

Originally Posted by ZeBoost

By the way, the car still shows this code. Someone a few posts up mentioned an issue that could be possible due to the low pressure fuel pump. The car runs great but I still cannot figure out this code. A local indi mechanic even suggested the car could've had an ECU or engine swap at some point!

If I ever sort this out, I'll come back to clean out this thread. I still have a few things to do on the car but overall it runs well enough to be my daily so it's not a priority but still on the very long list of things to do.

That must be so irritating ideal with. I looked on mine and It's in the same place as the N54 which is right where yours isn't. What was your code exactly? Are you sure it's not the part on the fuel Line itself? Also it could be your DME that is bugged out. A 535i I once fixed has the same code and we changed the sensor and tried to clear the code and it wouldn't. We tried on 3 different tools. Then we went and changed the pump all other sensors and still toproblem remained. I then decided to check the DME and sure thing the code went away. i even put back on his old sensor and pump and the code was gone. I plugged back in the old DME and the code returned. I'm wondering though if you have followed the line and checked every sensor. If you have the stock line the sensoyou are looking for is Brass in color and sticks out easily. If. You find it and it doesn't erase the code then check the DME. I just hope it's not the low pressure sensor that is inside the gas tank. There are two sensors on there the high pressure sensor is on the side of the gas tank that you can pull out the low pressure sensor is on the other side and you can't take it out... The only way to change that sucker is with the whole gas tank being changed. Hope any of this info checked. Btw My three buds all said it's either the sensor on the line or the gas tank. I say it might be the DME. However if the system is saying the low pressure sensor is bad it's because there is 100% without a doubt a sensor there. Just not on the block i guess your engine was mostly pit on in the UK i heard. They have them over there without a sensor on the block you should look around a UK forum and ask. If you are plugged into your cars system with the BMW app look at the fuel pressure rating there. The low should be on 72. The low pressure sensor tells the high pressure sensor what to do pretty much. If it's really bad it can be messing up the whole pump and even the engine to the point where it won't stay on when you start the car so try finding osensor before you drive around over 300miles or so because it will get bad. Of on the app the low pressure sensor is at 72 you should have no problem the high pressure is at 120-140ish depending on how you are driving.

Ryanlocc · 08-24-2021, 05:32 AM

[QUOTE=ZeBoost;27919184]By the way, the car still shows this code. Someone a few posts up mentioned an issue that could be possible due to the low pressure fuel pump. The car runs great but I still cannot figure out this code. A local indi mechanic even suggested the car could've had an ECU or engine swap at some point!

What is that Sensor plugged in on the block next to the red arrow?

ZeBoost · 08-24-2021, 01:29 PM

Thanks for the info, I too lean toward the DME having an issue but now there could be a low pressure sensor in the tank and that's why I can't spot it. The low side does read 72 via the app, I haven't connected an actual gauge to the low side to see what it says. I have traced the fuel line (low pressure before the HPFP) all the way from the back of the HPFP to the firewall and there is no sensor anywhere on the line. The red arrow in the original picture points to where the sensor should be but on my car it's just a solid metal piece, no way to screw a sensor in.

It's a strange issue but the car runs pretty good overall. Thanks for the insight, I'm going to check out some UK forums and see if I can spot another with the same issue. It's actually going to the shop sometime soon for a fuel system diagnostic to see if I can sort out a small misfire at idle that comes and goes, I'm going to have them take another look at the fuel sensor code as well.

PepMo · 03-10-2022, 03:53 AM

I read that F10 535i with production dates prior to 9-2011 does have low pressure sensor. So you must have mismatched DME. Someone must have damaged the original DME and purchased a used one from an older model F10? Or the mistake was made at the the factory.

https://www.ecstuning.com/b-genuine-...xoC9TAQAvD_BwE

ZeBoost · 03-10-2022, 01:37 PM

It’s an odd one, I pulled the intake manifold off when I did the HPFP and I can confirm there is no sensor where it should be. It’s possible the LP fuel line was replaced or DME was swapped. The one I’m starting to think is there could be a LP fuel sensor in the LP fuel pump. I’ve also seen some schematics from the old style HPFP from Continental that show a fuel pressure wire in the HPFP harness.

The car runs pretty good so I’ve placed this issue on the back burner. Thanks for the input!

SC BMWs · 02-29-2024, 11:02 PM

Unicorn here: 2011 F25 N55 96K miles, production date 201102

I hope this post helps others in the same lurch.

My X3 has been starting hard for the last 18 months. Started stalling and going into limp mode more recently. My Autel scanner was reading 45ish PSI low pressure, 2,300+ PSI high pressure under load.

Replaced lpfp in tank with a Walboro 450 (to future proof) and still starts hard, still idles rough but no more stalls. Autel now reads 101.53 low side psi and doesn’t change during live feeds. In fact, never changes. I figured it’s time to replace the low pressure fuel sensor on the feed line.

Just popped off the intake and…. no sensor on the feed rail.

I saw a youtube video by The 50’s Kid where he’s changing it our on an e90 and he mentions that some BMWs use a chart or something?

Anyway, for ZeBoost, get the Walboro 450 kit and I’m sure you’ll be feeding the hpfp with plenty of gas so it doesn’t have to suck it out. (Also, I strongly suggest getting an $18 lock ring opener from Amazon. Best money you’ll ever spend).

Any other information on how these cars are getting low pressure data would be greatly appreciated.

ZeBoost · 03-01-2024, 10:31 AM

I've spoken to a handful of people about the missing low pressure fuel switch, and it seems, there were indeed early f10s that did not include it. Supposedly the car determines LP fuel needs via various sensors and a DME map.

My hard starts went away completely once I replaced the HPFP. It was bit expensive but I figure I won't need to replace it again. As it stands now, the car runs fairly good. There is still a bit of a misfire at idle when cold, but I've decided to live with it as the car runs strong and starts right up every time.

My current dilemma is whether or not I do the rod bearings during the oil pan gasket job I have to do here in the next 2-3 weeks!

01-21-2020, 08:52 AM	#1
kenlena46 Registered 6 Rep 4 Posts Drives: 2011 BMW 535i Join Date: Jul 2019 Location: Arizona iTrader: (0)	N55 No Low Fuel Pressure Sensor??? HELP!!! I need some help here and need to pick all your brains. My 2011 535i N55 had a check engine light come on so I took it to the mechanic to see what was going on. He said the coolant temperature sensor isn’t working correctly and he thinks I need a new sensor or it has some sort of electrical problem/short going on. He also said the car is giving a code for the low fuel pressure sensor so he advised me to take it to the BMW dealer to have them go through it because he thought it had to do with an electrical problem. I took it into the dealership and they said the coolant temperature sensor was bad and needed to be replaced and the low fuel pressure sensor was bad and needed to be replaced as well. Because they wanted to charge me over $800 to do the job I decided it all looked fairly easy and I could do it myself. I got the parts from BMW and went to do the work. I noticed as I was looking for the low fuel pressure sensor that it was nowhere to be found. I did some research and found out that my vehicle wasn’t produced with a low fuel pressure sensor (N55 motor). So I went back to BMW and told them what I found and asked for them to find the reason my vehicle was putting out this code if the vehicle was made without that sensor. They ended up telling me that they have no clue why it does not have the low fuel pressure sensor and that they think I had my motor swapped at some point and during that process they deleted the sensor which is all BS! I asked them to provide me with pictures of the different vin number they found on the engine and they wouldn’t provide me with them. So their solution to the problem was we can take the vehicle in on trade and give you a great deal on a new BMW and that’s all they could do. I’m just looking to see if anyone else has experienced this whole no low fuel pressure sensor thing??? Attached Images
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01-22-2020, 08:31 AM	#2
95blkmax Captain 210 Rep 656 Posts Drives: '11 535 M-Sport Join Date: Nov 2019 Location: Oklahoma City iTrader: (0)	you HAVE to have a low pressure sensor. It's the only way the DME knows that your LPFP is working within operating range. It's on the fuel line feeding the HPFP. See this diagram from realoem (SEE ITEM #7) https://www.realoem.com/bmw/enUS/sho...diagId=13_1355. The coolant temp sensor IS the one you have pictures on the side of the block under the IM. You're almost there buddy you got this! __________________ I'm on the YouTubez now!! Check it out -> https://www.youtube.com/@turbospool 11' M-sport- 371WHP - 478WTQ on stock PWG E50 TunedbyShoup // 386WHP - 429WTQ on Shuenk N55+ with ultra-conservative 91 Octane tune // Starting full-range flexfuel tuning in Spring '24
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01-07-2021, 10:37 PM	#6
ZeBoost New Member 2 Rep 20 Posts Drives: F10 535i / E36 M3 Join Date: Jan 2021 Location: Phoenix, AZ iTrader: (0)	Hello All, My, my it's a small world after all. I believe I purchased the vehicle that OP posted about! I was Googling for a solution to this odd error code and came across this post. When I purchased the car from OP, it needed an alternator. I purchased an OEM alternator (Bosch) as I couldn't find the original Denso. After the swap, the car fired up (long crank) and ran rough (random misfires) but alternator was indeed charging the system. After a few short drives, the car went into an odd limp mode. The iDrive went dark, the instrument cluster looked like an Xmas tree and the car had about 5% power. I just managed to get it off to the side of the road. I turned it off, then back on and it fired back up (still long crank, still misfiring) and got me home. I checked the codes and there were multiple modules listing over voltage messages. Long story short, I purchased an alternator direct from BMW and installed it and that took care of the over voltage issues (still long cranks, still misfires). The pics that OP posted are accurate, the car indeed does not have a LP sensor, at least not where it should be. The HPFP supply line has a hex shaped knob with no way to install a sensor. This brings us to my current dilemma, the car is still long cranking and still misfiring at idle and is throwing a LP sensor code: 119202 FUEL LOW PRESSURE SENSOR, ELECTRICAL: SHORT TO GROUND My next step will be to determine where this phantom sensor plugs into the DME and confirm whether or not, there are wires there and if they are shorted to ground. But if anyone on the forum can provide some insight into this code, I would greatly appreciate it. For those wondering, HPFP looks good at the rail. I've logged crank, idle and light + medium loads. It has new BMW Bosch plugs and coils. Also, via the rail sensor I can confirm that the car shows a good LPFP before it cranks. An interesting bit of info, the car does show a LP sensor reading that stays pinned. No idea where that reading comes from (DME default possible). Thanks everyone! PS. An interesting development, when the car is in Sport or Sport +, 80% of the rough idle disappears.
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01-07-2021, 10:47 PM	#7
AZ-MCRacer First Lieutenant 306 Rep 332 Posts Drives: 2022 G82 M4, 2013 F10 N55 Join Date: Oct 2016 Location: Tempe, AZ iTrader: (0)	I don't think any of the N55's have a LPFP pressure sensor. __________________ 2022 G82 M4 - Isle of Man Green w/Kyalami Carbon Bucket Seats - MST Intakes, SSR Downpipes, JB4, AWE Exhaust. 2013 F10 N55 (535i), Pure Stage 2, Fuel-It PI Platinum, Fuel-It Stage 2 LPFP, BootMod3, Custom Turbo Inlet, Custom Cary Jordan Tune, More.. SOLD! 1999 e36 M3 - Estoril Blue - Track Car - S54 Swapped
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01-08-2021, 02:17 AM	#8
ZeBoost New Member 2 Rep 20 Posts Drives: F10 535i / E36 M3 Join Date: Jan 2021 Location: Phoenix, AZ iTrader: (0)	The strange part is that this car doesn’t but the DME thinks it does and it’s shorted.
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01-23-2021, 12:49 AM	#9
ZeBoost New Member 2 Rep 20 Posts Drives: F10 535i / E36 M3 Join Date: Jan 2021 Location: Phoenix, AZ iTrader: (0)	Hello All, Just to keep those who've responded and those who may be curious about the vehicle updated, I was able to run diagnostics through INPA and the HPFP appears to be the issue. Fuel pressure at crank takes too long to build and at idle it fluctuates enough to potentially be the cause of my misfires. When the car is at higher RPMs the pump is able to keep up, which is why I don't feel the misfires anywhere but idle. This more than likely points to seal degradation inside of the HPFP. I've ordered a new HPFP, misc gaskets and a new HP sensor from ECS as part of a kit they offer. I should have the parts installed in the next 1-2 weeks and will report back then. But the shadow code for the LP fuel sensor short (when the car doesn't have a LP fuel sensor) is still a mystery. I have verified with my own eyes that the car does not have a LPFS, at least were it's supposed to be. TO BE CONTINUED...
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02-04-2021, 04:11 PM	#10
ZeBoost New Member 2 Rep 20 Posts Drives: F10 535i / E36 M3 Join Date: Jan 2021 Location: Phoenix, AZ iTrader: (0)	A quick update for those interested and those who may stumble on this thread, I received the HPFP kit from ECS yesterday and will be installing this weekend. Once it's in, I'll report back.
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02-16-2021, 07:39 PM	#11
ZeBoost New Member 2 Rep 20 Posts Drives: F10 535i / E36 M3 Join Date: Jan 2021 Location: Phoenix, AZ iTrader: (0)	An update for anyone who may stumble on this thread: after swapping out the HPFP and HP fuel sensor, the long crank is now resolved. The car fires up in about half a second every time; cold, hot, sitting for a while, turn off and back on, etc. It doesn't matter, the car fires right up every single time. But the intermittent miss at idle is still there. I used new gaskets and was careful putting everything back together again. The carbon build up at the valves didn't look too bad. I'm now suspecting I have a vacuum leak as the car runs strong everywhere in the rev range, doesn't smell rich or foul plugs (no CEL or shadow codes related to misfire, fuel, ignition, etc.). The next step will be a smoke test to see if I can find a leak.
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07-01-2021, 11:51 AM	#12
F10_User Enlisted Member 16 Rep 39 Posts Drives: X5 Join Date: Jan 2019 Location: AZ iTrader: (0) Garage List 2022 bmw x5 [0.00] 2015 bmw 535i [0.00]	https://static.nhtsa.gov/odi/tsbs/20...46992-9999.pdf recall on some vehicles.
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07-01-2021, 12:13 PM	#13
ZeBoost New Member 2 Rep 20 Posts Drives: F10 535i / E36 M3 Join Date: Jan 2021 Location: Phoenix, AZ iTrader: (0)	Thank you very much for sharing this! I did perform a smoke test and found no leaks under the hood but the slight miss is still there. I have two more items I am going to check: 1. An internal vacuum leak at the valve cover vacuum reservoir and 2. O2 sensor voltages, response time. But I am now going to have another look for possible issues at the NVLD.
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08-13-2021, 11:11 PM	#14
Ryanlocc 4mEVO92535I 0 Rep 3 Posts Drives: 2011 535I M Sport Join Date: Aug 2021 Location: CA iTrader: (0)	[QUOTE=ZeBoost;27095791]Hello All, . The pics that OP posted are accurate, the car indeed does not have a LP sensor, at least not where it should be. The HPFP supply line has a hex shaped knob with no way to install a sensor. This is very interesting I have heard of this before though. I saw a few guys tslking about it on another forum one of them said that he was tired of it showing the code and another brought up that there are some N55s out there without that LPFP and that with that engine he wouldn't have a problem and now i this thread. But it weird because you say its not there yet it throws a code it makes me wonder what the problem is. My bmw threw the same code but ay the end it said short circuit to B+ which BMW said IS the sensor. Im guessing your problem is that its shorting out at the ground and that your cable has became ungrounded. I will ask my friend at BMW tmrw and report back but this is a curious one. The no LPFP N55 unicorn exists. Let em know.
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08-14-2021, 12:25 AM	#15
ZeBoost New Member 2 Rep 20 Posts Drives: F10 535i / E36 M3 Join Date: Jan 2021 Location: Phoenix, AZ iTrader: (0)	By the way, the car still shows this code. Someone a few posts up mentioned an issue that could be possible due to the low pressure fuel pump. The car runs great but I still cannot figure out this code. A local indi mechanic even suggested the car could've had an ECU or engine swap at some point! If I ever sort this out, I'll come back to clean out this thread. I still have a few things to do on the car but overall it runs well enough to be my daily so it's not a priority but still on the very long list of things to do.
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08-24-2021, 05:32 AM	#17
Ryanlocc 4mEVO92535I 0 Rep 3 Posts Drives: 2011 535I M Sport Join Date: Aug 2021 Location: CA iTrader: (0)	[QUOTE=ZeBoost;27919184]By the way, the car still shows this code. Someone a few posts up mentioned an issue that could be possible due to the low pressure fuel pump. The car runs great but I still cannot figure out this code. A local indi mechanic even suggested the car could've had an ECU or engine swap at some point! What is that Sensor plugged in on the block next to the red arrow?
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08-24-2021, 01:29 PM	#18
ZeBoost New Member 2 Rep 20 Posts Drives: F10 535i / E36 M3 Join Date: Jan 2021 Location: Phoenix, AZ iTrader: (0)	Thanks for the info, I too lean toward the DME having an issue but now there could be a low pressure sensor in the tank and that's why I can't spot it. The low side does read 72 via the app, I haven't connected an actual gauge to the low side to see what it says. I have traced the fuel line (low pressure before the HPFP) all the way from the back of the HPFP to the firewall and there is no sensor anywhere on the line. The red arrow in the original picture points to where the sensor should be but on my car it's just a solid metal piece, no way to screw a sensor in. It's a strange issue but the car runs pretty good overall. Thanks for the insight, I'm going to check out some UK forums and see if I can spot another with the same issue. It's actually going to the shop sometime soon for a fuel system diagnostic to see if I can sort out a small misfire at idle that comes and goes, I'm going to have them take another look at the fuel sensor code as well.
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03-10-2022, 03:53 AM	#19
PepMo Private First Class 18 Rep 104 Posts Drives: 2014 535i Join Date: Jul 2019 Location: CA iTrader: (0)	I read that F10 535i with production dates prior to 9-2011 does have low pressure sensor. So you must have mismatched DME. Someone must have damaged the original DME and purchased a used one from an older model F10? Or the mistake was made at the the factory. https://www.ecstuning.com/b-genuine-...xoC9TAQAvD_BwE
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03-10-2022, 01:37 PM	#20
ZeBoost New Member 2 Rep 20 Posts Drives: F10 535i / E36 M3 Join Date: Jan 2021 Location: Phoenix, AZ iTrader: (0)	It’s an odd one, I pulled the intake manifold off when I did the HPFP and I can confirm there is no sensor where it should be. It’s possible the LP fuel line was replaced or DME was swapped. The one I’m starting to think is there could be a LP fuel sensor in the LP fuel pump. I’ve also seen some schematics from the old style HPFP from Continental that show a fuel pressure wire in the HPFP harness. The car runs pretty good so I’ve placed this issue on the back burner. Thanks for the input!
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02-29-2024, 11:02 PM	#21
SC BMWs Registered 1 Rep 4 Posts Drives: '04 X3 2.5, ’07 335i MT Coupe Join Date: Jun 2012 Location: South Carolina iTrader: (0)	Unicorn here: 2011 F25 N55 96K miles, production date 201102 I hope this post helps others in the same lurch. My X3 has been starting hard for the last 18 months. Started stalling and going into limp mode more recently. My Autel scanner was reading 45ish PSI low pressure, 2,300+ PSI high pressure under load. Replaced lpfp in tank with a Walboro 450 (to future proof) and still starts hard, still idles rough but no more stalls. Autel now reads 101.53 low side psi and doesn’t change during live feeds. In fact, never changes. I figured it’s time to replace the low pressure fuel sensor on the feed line. Just popped off the intake and…. no sensor on the feed rail. I saw a youtube video by The 50’s Kid where he’s changing it our on an e90 and he mentions that some BMWs use a chart or something? Anyway, for ZeBoost, get the Walboro 450 kit and I’m sure you’ll be feeding the hpfp with plenty of gas so it doesn’t have to suck it out. (Also, I strongly suggest getting an $18 lock ring opener from Amazon. Best money you’ll ever spend). Any other information on how these cars are getting low pressure data would be greatly appreciated.
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03-01-2024, 10:31 AM	#22
ZeBoost New Member 2 Rep 20 Posts Drives: F10 535i / E36 M3 Join Date: Jan 2021 Location: Phoenix, AZ iTrader: (0)	I've spoken to a handful of people about the missing low pressure fuel switch, and it seems, there were indeed early f10s that did not include it. Supposedly the car determines LP fuel needs via various sensors and a DME map. My hard starts went away completely once I replaced the HPFP. It was bit expensive but I figure I won't need to replace it again. As it stands now, the car runs fairly good. There is still a bit of a misfire at idle when cold, but I've decided to live with it as the car runs strong and starts right up every time. My current dilemma is whether or not I do the rod bearings during the oil pan gasket job I have to do here in the next 2-3 weeks!
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