[Mr.F10_4.4TT]

Hello guys
I can really really use some help on this issue.

2011 535i
Purchased from the auction with a blown engine.

I replaced the engine with a used motor with 78k. Engine starts and runs perfectly fine.

This issue I'm having is this, the cooling fan is not kicking in when the engine temp is hot so the car overheats.

Replaced the cooling temp sensor (at the front of engine), still no go. A new water pump, thermostat, and radiator fan, plus fan relay (in the trunk ) has been installed.

Things to consider

1- I can active the fan with my scan tool
2- With the engine running, temp sensor connector plugged into a sensor that is not mounted on the engine, I can heated the sensor with a lighter and the fan would come on.
3- no codes in system
4- At times I can see the fan signal on my scanner in special operations, and at times the values sits at 7.03% and never moves

5- fan turns on if the temp sensor is unplugged
6- 12v at heavy gage fan wire @ the connector and after he connector.
7- 12v at signal wire from ecu

I'm really out of options here guys any help would be super appreciated!

[ezaircon4jc]

Bad sensor? They have been known to be bad right out of the box. Put the "test" sensor (the one you used in #2) in the engine and see what happens (unless it's the same sensor and then I got nutin')

[Mr.F10_4.4TT]

Originally Posted by ezaircon4jc

Bad sensor? They have been known to be bad right out of the box. Put the "test" sensor (the one you used in #2) in the engine and see what happens (unless it's the same sensor and then I got nutin')

Originally Posted by ezaircon4jc

Bad sensor? They have been known to be bad right out of the box. Put the "test" sensor (the one you used in #2) in the engine and see what happens (unless it's the same sensor and then I got nutin')

Okay, so, I removed the sensor first when I noticed the issue and realized the fan will work with the sensor unplugged. So I ordered a new one and put it in, same thing. Left the new one mounted on the car, unplugged the connectors and plugged it to the old sensor thaw as in the car, when while it idled that's the sensors I heated with the lighter.

But you would recommend a new sensor either way is what you're saying?

[ezaircon4jc]

Originally Posted by Mr.F10_4.4TT

Okay, so, I removed the sensor first when I noticed the issue and realized the fan will work with the sensor unplugged. So I ordered a new one and put it in, same thing. Left the new one mounted on the car, unplugged the connectors and plugged it to the old sensor thaw as in the car, when while it idled that's the sensors I heated with the lighter.

But you would recommend a new sensor either way is what you're saying?

Have you tried both sensors out of the engine?

[Mr.F10_4.4TT]

Originally Posted by ezaircon4jc

Have you tried both sensors out of the engine?

No, I have not, just the original sensor.

[ezaircon4jc]

Originally Posted by Mr.F10_4.4TT

No, I have not, just the original sensor.

Try that first. If they both work outside the engine check and make sure the threads (engine and sensor) are clean.

[Mr.F10_4.4TT]

Originally Posted by ezaircon4jc

Try that first If they both work outside the engine check and make sure the threads are clean.

The thread for the sensor? It is clean. The sensors screws in to the head fine.

[Mr.F10_4.4TT]

Originally Posted by Mr.F10_4.4TT

The thread for the sensor? It is clean. The sensors screws in to the head fine.

Any help here guys, this thing is becoming a nightmare:/