I had this on mine. Tried all the usual maf tests and had the fault codes read. Richard gave me the interpretation of the codes and I explored all avenues, finally biting the bullet and fitting a new throttle body, as the test maf from my local indie came up with the same fault codes and c.e.l. it started of as a bit annoying and got to the point where it wanted to idle at 1800 rpm. Lost all power on the M3 just as I booted it off the slip road and had abs and pasm failure warnings then it chimed in so I got it up to speed then drove very gingerly to where I was going. After the retstart it was ok for the journey home but then I decided something had to be done. When I took it apart I found that some fathead had fitted a cloth/mesh filter similar to K&N but it was for the carrera with the cut out to clean the ac pump L x W it fitted in the same rectangle but the cut out meant that some of the air was not properly filtered luckily it would only have been at full rpm, but some debis was trapped in the very thin mesh behind the coarse mesh in the filter and it could have been that this deris was disrupting the laminar flow of the airstream into the maf. Anywy with the piping all off and the t/b purchased I was not about to put the old one back in after discovering that, by way of a test, so in went the new one with a new rubber seal and it is as good as gold now. I hope for your wallet it turns out to be nothing more than a dirty maf because a throttle body cost me £670 plus vat.
