[Len_Beach]

I have a 330d LCI which has consistently returned about 36mpg.

I've never had a huge issue with this as I suspected it was due to my driving. Last week; I decided to look into it further.

Temps are fine so I moved onto the MAF and MAP sensors. I cleaned the MAF with contact cleaner, no issues there.

I then took the MAP sensor out which was very sooty so I cleaned that with contact.

The car runs fine and is returning around 40mpg now after 250 miles.

I haven't scanned my codes for ages. When I did it after cleaning; I got 3FC0 - Air flow Meter - Deviation too high at idle speed. This code won't clear and immediately reappears even when the car isn't started.

I suspected a MAF issue. When I unplugged the MAF I got 4BC2 - Air flow Meter - Short circuit plus 3F70 - Intake Air temperature Sensor - Signal

Given that fresh codes appeared when I unplugged the MAF and the original remained; I'm a little confused as to whether this is a MAP or MAF issue.

The car runs fine and the idle is spot on 650rpm.

[Len_Beach]

Any ideas Guys?

I thought about reseting adaptations?

[kkasson]

I'm not sure about the solution, but 3FC0 is indeed for the mass airflow sensor.

[Len_Beach]

Thanks Chaps.

I'll try cleaning it again and resetting adaptations.

[Will184]

I had the same code in my car. I just sprayed some contactspray on the connector of the maf sensor. And i put the connector in and out a few times. Now i can clear the fault code and is does not come back.

[Len_Beach]

Thanks Buddy. This was due to the deviation in MAF reading following the cleaning.

Resetting adaptations solved the problem.