[CO335D]

Okay guys,

My car went into limp mode yesterday (yellow half engine light) and threw the following codes that stayed stored after being cleared:

4BC2 - air flow meter signal / air mass sensor / air mass meter

4BC6 - intake air temperature sensor / intake air mass air signal / inlet air temperature

I am assuming these are related to the MAF sensor, but please correct me if I am wrong. I have read these sensors are pretty touchy, so I carefully removed the sensor and sprayed it with some MAF cleaner. I could see some residue the was almost painted on top of the hot plate. I did not touch that, but did spray it pretty good with the MAF cleaner. It looks like it would need to be rubbed with something like a Q Tip to really remove it completely. I was afraid to touch it though, because I didn't want to break anything (I know they're expensive). Anyways, I re installed everything and cleared my codes... car started and codes instantly reappeared.

So, has anyone experienced these codes before? Any suggestions on making them disappear? Do I need to suck it up and pay for a new sensor?

[demon]

took my car to the dealer for maf codes. They could not clear and ordered a MAF. They were not sure if the new MAF was going to fix it so took the car for about 100 mile joy ride, a truck threw a rock through the windshield. They had the car for a week and a half. The code has not reappeared sense I got it back. .

[CO335D]

What's weird is that the car doesn't stay in limp mode. It goes in and out at random. No real rhyme or reason.

[iaknown]

Check the air temp sensor in the intercooler to throttle valve pipe. This sensor works together with the MAF. Do you have a way to read intake charge temp data? May want to check that 1st and make sure its not something obvious.

[CO335D]

Originally Posted by iaknown

Check the air temp sensor in the intercooler to throttle valve pipe. This sensor works together with the MAF. Do you have a way to read intake charge temp data? May want to check that 1st and make sure its not something obvious.

Would that be #18 in this picture?



I need to get a new wifi adapter to log and read real data. The BMWhat app is forcing people to buy theirs now.

[iaknown]

Yep that's it.

Do you have Torque? You could try that...There is a temp sensor in the MAF and that one in the tube. The one in the tube should read slightly higher.

[Yozh]

No 16 in the above diagram. No 18 is a clip.

[iaknown]

Originally Posted by Yozh

No 16 in the above diagram. No 18 is a clip.

Good thing somebody here is paying attention

[CO335D]

Haha, good call. My eyes didn't catch that. I will give it a look once I get off work. I don't have torque because I don't have an android unfortunately.

[CO335D]

Okay guys, finally getting around to pulling the IAT sensor and checking it out. Can anyone who has done this give me a little advice on the best way to get to the sensor/how to remove the retaining clip? Does the retaining clip just pry off the top?

[remlemasi]

Just received these codes (in addition to 4831) tonight. See other thread for BMWhat app report notes ("Checking for CBU").

Same symptoms as you: start engine and instant limp mode that goes away after a few minutes of driving.

For the time being, I'm assuming this is a CBU thing and will bring it in soon. Did you end up resolving this? Was it CBU?

Also weird that BMWhat app cleared only the BMW codes, but the equivalent OBD codes (0101 and 0112) remained.