[BimmerHausPerformance]

I've never done a tutorial before, and because I didn't easily find a plug and play fix I thought I'd share what I ended up doing on my F10 N55 and what I learned. This whole thing cost me less than 200 bucks and I'll include links to everything below.

I'm assuming that you have a head on your shoulders and I'm not going to walk you through every single detail but give you enough info to get the job done. I probably screwed up on some things, so if you have any observations feel free to call me out. Thanks!

Backstory: Bought this car from some rich lawyer for dirt cheap. 14,750 and only 71k and it's a true 6 SP.



Thought it was a great deal but I later found out it had no cat (which I would have done anyway) and he never disclosed anything. It should have been a clue he let me keep his plates and that the OBDII port door was hanging open from him clearing the codes before my test drive. Luckily it has about 4k in exhaust and ECU mods I would have done myself. I need to get through emissions where they will only do a visual (that I already passed) and plug into my ECU for a readiness check with no codes. To fix properly the Catted DP from BMW was roughly 1800 not including labor, no thanks.

Disclaimer: I am not a mechanic, and I really have no idea what I'm doing, so if you take my advice, don't come looking for me. If you learn from my mistakes, that's more of the point here! Remember, I'm really not that smart, I'm just good at repeating smart things I've read.

Symptoms: ECU Throwing PO13E and/or P013A codes due to the fact that you had to get rid of your cats because of an allergic reaction that isn't your fault at all.



Root Cause: For the POST CAT O2 sensor, the ECU is looking for a fluctuating reading from .75 (richest acceptable value) up to .95 volts (leanest acceptable value). As implied in the previous sentence, your ECU will adjust fuel based on the feedback from this Sensor, so it's nice to have an adjustable simulator.

Advantage of this fix:

1. It's pretty much Plug and Play and fully reversible in 5 minutes
2. It's not expensive
3. It'll pass emissions where they ONLY plug into your ECU without a sniff test
4. It allows you to adjust your fuel mixture
5. Doesn't mask other important CEL messages

OK so here it is:

Get your stuff together:

1. O2 Simulator (Link below)
2. Cheap O2 Sensor to steal the plug from (Link below)
   
   
   
3. Wire for a run to a cool place in the engine bay
4. Shrink wrap, Wire Conduit, Elec tape
5. Inline Fuse holder, 5A fuse
   
   
   
6. OBDII Reader and App (Links below)
   
   
   
7. Sodering tools - I recommend this for anywhere you can, it can get hot and it's better than connectors.

Prep for the job

1. Unplug Battery
   
   
   
2. Remove Engine Cover
3. Remove Top of air Intake
4. Remove Intake section with MAP sensor (by the way this will throw a code if you don't seat the silicone boot correctly between this section of pipe and the air box when putting things back together, found out the hard way)
5. Plug Intake (I used a sponge)
   
   

Install:

Location: It's recommended you install this away from heat. This thing gets HOT. So I decided to run the wires across the back of the firewall and put this thing up front near the air intake on the DS.

Wiring: The module has 6 wires coming out of it. Black for ground - I just loosened the bolt on the brace and secured it there.
Red for 12V Power - You want switched power here. I used the center wire on this plug since it was close. I just tapped into it. Posi Taps are good (google it), don't use crappy Autozone wire taps, please. This appears to be the control for the valve that I assume opens up the coolant lines going into your heater core. I hope this works when I turn my heat on. Make sure you put a 5 amp in line fuse on this just to protect it. Don't want it to spike and burn up your simulator. (Pics below)
Then the other 4 go to the O2 Sensor Plug @ the harness. (Just match these up per the instructions it comes with)





Mounting the Simulator: I removed a screw and it's anchor on the inner DS wheel shrowd and used that hole to secure the post through. From inside the wheel well:

Wiring in the Plug: Per the instructions. I just hacked this plug off of the new part I got off ebay... well worth it to not cut into your BMW.



Next, I hid the wires, zipped them up and switched out the actual O2 plug for the plug now running to the Simulator. I hung the old plug in a nice spot that is easily accessible in case you want to switch it back. Remember you want the GRAY plug on the side close to the firewall.

Startup:

Remove or disable any ECU modifying equipment.

Turn accessories on without starting the car.

Clear codes through app.



Set up a custom Dashboard with O2 Sensor readout with 2 decimal places.



Start the car, you'll see a fluctuating reading of up to .95 or .96 Volts. This is ADJUSTABLE. .95 is as lean as OBD II will read without a code. I'll probably adjust this to .75 which is as rich as you can get and not trip a code. Adjusting is easily done by opening up the simulator and using the adjustment screws.



PRO TIP (haha): Instead of guess-and-check which the instructions tell you to do when adjusting, you can use your app to check voltage... or a voltage meter if you want to mess with that.

Parts List:

O2 Simulator: https://www.magnumtuning.com/en/deta...lator/bmw/535i

02 Sensor to Harvest Harness: https://www.ebay.com/itm/O2-Oxygen-S...72.m2749.l2649

OBD II BT Scanner: https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1

OBD II App: https://www.obdsoftware.net/software/obdfusion

Thanks for reading let me know if you have any questions.

[trialmountain]

Great work for what it is. That said, why not just get a proper tune (BM3/MHD) that hides the code and gives you proper/active calibration for not having a cat?

[BimmerHausPerformance]

Fair question. Hiding the code doesn't get me through emissions in TN. They have to plug in and see the ECU in ready state and no codes. If I just mask it, then that doesn't help.

Long term, I'm looking at a turbo upgrade where I'll get it tuned properly, so this is just so I can get my plates.

Or maybe I'm misinformed - if I flash with one of those mods, would my OBD2 port be open and available for them to scan, would they not see anything? Would the car reach ready state?

[ziekxq]

I think they code it so that the car is always in ready state.

[trialmountain]

Originally Posted by BrowBMW

Fair question. Hiding the code doesn't get me through emissions in TN. They have to plug in and see the ECU in ready state and no codes. If I just mask it, then that doesn't help.

Long term, I'm looking at a turbo upgrade where I'll get it tuned properly, so this is just so I can get my plates.

Or maybe I'm misinformed - if I flash with one of those mods, would my OBD2 port be open and available for them to scan, would they not see anything? Would the car reach ready state?

The tunes flash the car into a ready state and pass OBD with flying colors in WA state. You do not need to have something constantly plugged into the OBD port with MHD or BM3.

[BimmerHausPerformance]

Oh well, that would have been nice to know 2 WEEKS AGO, lol... thanks guys.

[BimmerHausPerformance]

Quick update for anyone reading this... It passed emissions and got me into readiness state. Also, even after re-chipping the car and leaving the simulator plugged in it has not thrown a code. It shows some pending codes, but nothing has moved to permanent yet which will throw the CEL.

[ziekxq]

I just passed the emission as well. All I got is a spacer on my downpipe that does the trick. MHD by default disables the Catalytic converter check, so you have to make sure that OEM/Catted-DP tick is checked.

[Thecastle]

Why don’t you guys use 02 sensor spacers? To trick the 02 sensor reading.

[rockyfeller]

Awesome writeup, thank you. I'm looking into doing a similar CEL solution. I'm assuming this is still running along fine?

I was going to go with another solution by A74 (can't spell out the full name here, forum edits it) but it doesn't seem to work with the more recent BMWs.

So the box only sends signals upstream, to where the O2 sensor plugs into the car, correct? There are no downstream connections (towards the downpipe) from the Magnum tuning box I assume? I'm asking because I'm trying to do a plug in solution like you and not hack up the O2 sensor wiring. All I'll need is the female side of the O2 harness as a donor to splice in?

[BimmerHausPerformance]

Originally Posted by rockyfeller

Awesome writeup, thank you. I'm looking into doing a similar CEL solution. I'm assuming this is still running along fine?

I was going to go with another solution by A74 (can't spell out the full name here, forum edits it) but it doesn't seem to work with the more recent BMWs.

So the box only sends signals upstream, to where the O2 sensor plugs into the car, correct? There are no downstream connections (towards the downpipe) from the Magnum tuning box I assume? I'm asking because I'm trying to do a plug in solution like you and not hack up the O2 sensor wiring. All I'll need is the female side of the O2 harness as a donor to splice in?

I went MHD because that flashes the car into ready state so that was my long term solution. But you are right, it fools the ECU and sends an acceptable value upstream. I bought a CHEAP eBay 02 and stole the plug off of it so it was fully reversible.

[rockyfeller]

I have a question about how you tapped in for the 12V source. You said you tapped the center wire of the plug. Which wire was it? Do you mean the O2 heater wire for the sensor itself? If not, can the O2 heater wire be used as a 12V source?

I have seen in some places it's been used this way. And somewhere else it's been said not to tap this wire and use an independent switched 12V source. If I had to find another source it wouldn't be too easy, using the O2 connector itself is much easier. But I'm not going to risk damage to me DME's if that's the concern.

[BimmerHausPerformance]

Originally Posted by rockyfeller

I have a question about how you tapped in for the 12V source. You said you tapped the center wire of the plug. Which wire was it? Do you mean the O2 heater wire for the sensor itself? If not, can the O2 heater wire be used as a 12V source?

I have seen in some places it's been used this way. And somewhere else it's been said not to tap this wire and use an independent switched 12V source. If I had to find another source it wouldn't be too easy, using the O2 connector itself is much easier. But I'm not going to risk damage to me DME's if that's the concern.

Lucky you I am in my engine bay right now… this is what I used to get 12V switched. Driver side

[rockyfeller]

Thanks, ok so you went with an external source. Any reason you didn't opt for using the O2 sensor heating wire that's right in the O2 sensor harness itself? Is it safe to use?

[Unspec]

Root Cause: For the POST CAT O2 sensor, the ECU is looking for a fluctuating reading from .75 (richest acceptable value) up to .95 volts (leanest acceptable value). As implied in the previous sentence, your ECU will adjust fuel based on the feedback from this Sensor, so it's nice to have an adjustable simulator.

Just a quick clarification: Post cat sensor does not affect fuel trim in any way. It's the pre cat sensor that does that. The post cat O2 sensor is purely to monitor the efficiency of the cat and is only used for emissions purposes.

[BimmerHausPerformance]

Originally Posted by rockyfeller

Thanks, ok so you went with an external source. Any reason you didn't opt for using the O2 sensor heating wire that's right in the O2 sensor harness itself? Is it safe to use?

I couldn't say… sorry!

[rockyfeller]

Ok no worries.

After looking at Magnum's instructions they specially say not to tap the O2 heater power so I won't. Pretty sure it's risk to the DMEs and not worth it.

[BimmerHausPerformance]

Originally Posted by rockyfeller

Ok no worries.

After looking at Magnum's instructions they specially say not to tap the O2 heater power so I won't. Pretty sure it's risk to the DMEs and not worth it.

Why are you not just doing mhd?

[rockyfeller]

Originally Posted by BrowBMW

Why are you not just doing mhd?

My car is under extended warranty and I don't want to void it. Otherwise I'd do a tune in a heartbeat.

[BimmerHausPerformance]

Originally Posted by rockyfeller

My car is under extended warranty and I don't want to void it. Otherwise I'd do a tune in a heartbeat.

Ah that's right! This works then.

[rockyfeller]

I've did the install a few days back and it hasn't been successful so far. I know it's all wired up properly because the blue LEDs light up on the modules and I can see the simulated voltage readings when checking them with an OBD app. So that means the signal is going to the DMEs and it's all wired up properly for sure.

The modules are set at .95V from the factory and I can see the expected fluctuation up and down close to zero on the app. But I still got the CEL. I tried adjusting and clearing the code multiple times. I actually tried in .5V increments from as low as .65V all the way up to 1.05V. I was thinking that perhaps there was some magic value at which it might work? No dice. No matter what the CEL kept coming back.

So Brow, did you actually have to adjust the voltage on your car? If so, what value worked for you?

And the other thing that's stumping me is that by wiring it the way we are instructed to, it means that we're effectively cutting the power to the O2 heater wires. My car was showing this error code as well. Was it showing a code for the "O2 heater circuit not working" on your car? I'm not sure if this in itself would produce a CEL light or whether it would affect O2 sensor readiness?

If so, that poses a 2nd problem for getting this to work properly. But I'm less worried because it's an easier solution if that's the case. Just run separate wires directly to the O2 sensor so that the heater wires remain intact. There's no impact on the O2 heater element if there are cats or not.

Just to be clear, my car is a F10 M5, so it's a different engine than yours. S63. For the most part, from people who have tried, the consensus seems to be that the DMEs are hard to trick and so far nothing has worked. Perhaps the voltage fluctuations these type of simulators make are far too uniform and unrealistic so the car detects that something is not legit. That's my hunch.

Any input or advice before I throw in the towel?

[BimmerHausPerformance]

Originally Posted by rockyfeller

I've did the install a few days back and it hasn't been successful so far. I know it's all wired up properly because the blue LEDs light up on the modules and I can see the simulated voltage readings when checking them with an OBD app. So that means the signal is going to the DMEs and it's all wired up properly for sure.

The modules are set at .95V from the factory and I can see the expected fluctuation up and down close to zero on the app. But I still got the CEL. I tried adjusting and clearing the code multiple times. I actually tried in .5V increments from as low as .65V all the way up to 1.05V. I was thinking that perhaps there was some magic value at which it might work? No dice. No matter what the CEL kept coming back.

So Brow, did you actually have to adjust the voltage on your car? If so, what value worked for you?

And the other thing that's stumping me is that by wiring it the way we are instructed to, it means that we're effectively cutting the power to the O2 heater wires. My car was showing this error code as well. Was it showing a code for the "O2 heater circuit not working" on your car? I'm not sure if this in itself would produce a CEL light or whether it would affect O2 sensor readiness?

If so, that poses a 2nd problem for getting this to work properly. But I'm less worried because it's an easier solution if that's the case. Just run separate wires directly to the O2 sensor so that the heater wires remain intact. There's no impact on the O2 heater element if there are cats or not.

Just to be clear, my car is a F10 M5, so it's a different engine than yours. S63. For the most part, from people who have tried, the consensus seems to be that the DMEs are hard to trick and so far nothing has worked. Perhaps the voltage fluctuations these type of simulators make are far too uniform and unrealistic so the car detects that something is not legit. That's my hunch.

Any input or advice before I throw in the towel?

Oh wow, so do you have 2 downstream o2 sensors you need to trick? I researched the voltage on my application but I don't recall what it was exactly. I never got the other error message… sorry man, good luck!