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Marty, Mercedes Technician
Category: Mercedes
Satisfied Customers: 53946
Experience:  Bosch Certified Master Tech. Over 35 years experience.
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2005, W211 Chassis E500. CEL came on, and Threw Codes P0101

Customer Question

2005, W211 Chassis E500. CEL came on, and Threw Codes P0101 and P0410 . As soon as the CEL came on instantaneously now low end acceleration from either a stop or slow traffic, engine stutters and sometimes stalls out. Sometimes it behaves totally normal... Runs fine at speed.
I don't see any obvious vacuum line problems. I've cleaned the MAF, and no improvement. I'm not sure how the Secondary Airpump comes into play after the car is warmed up, and why it's throwing the P0410 code. Should I just assume the MAF broke and go down that path?
Submitted: 1 year ago.
Category: Mercedes
Expert:  Marty replied 1 year ago.

Hi, you can ignore the P0410 for the engine running problem. I would substitute a new MAF for the P0101 code. That should solve the engine running. The P0410 could be a bad air pump or plugged air passages in the heads. You will need to do a little testing for that code but it will not affect the engine running.

Customer: replied 1 year ago.
I got the P0410 about 2 years ago, and replaced the secondary air pump that had gone bad. But yea that only seems to be a startup issue and not anything to do with continued engine performance. I was curious if there is any way to test the MAF w/o having some diagnostic tool. It seems odd that it was such an instantaneous event, but perhaps if the sensor just crapped out that is the problem. It's particularly worse later in the day when it's really hot outside, and less of a problem in the early morning, not sure if that helps lead it to MAF replacement or not
Expert:  Marty replied 1 year ago.

Not much you can do without a scan tool that can read live data. The MAF should read between 4.5 - 5.5 grams per second at idle and approximately 170 grams per second at wide open throttle.