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x204 - P0101FB Permanent Code - HELP Needed

olavi

New Member
Joined
Jul 19, 2025
Messages
1
Location
Finland
Car
Mercedes Benz GLK x204
My car shows fault code P0101FB ("Mass Air Flow Sensor 1 malfunction"). Permanent Code, that cannot be erased.

  • Intake leaks between turbo and intercooler have been fixed.
  • Air filter replaced.
  • MAF sensor cleaned multiple times and adaptations reset.
  • MAF reading stable (~13.8 g/s at idle) - cleaning wont help, its always that reading, but the sensor itself does give like "reliable" data while driving, thats why i have not replaced it.
  • Original MAF sensor still installed - from 2012-2013 i believe.

Has anyone else experienced this code with similar conditions? What was the cause in your case? Any help appreciated!

I'm starting to get frustrated with the car, since it works pretty much normal, rpm might fluctuate a littlebit on idle, and acceleration does not respond as fast as usual, but still drives normal.
Is the MAF sensor faulty? is the MAP sensor faulty?

MAF does give normal readings when driving, i mean its higher than it probably should be, but it seems like the sensor works like sensor needs to work.

Any ideas?
 

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