OBD-II · Engine and powertrain (P)
P0101
Mass air flow range/performance
What it means
The measured air flow does not match the engine operating conditions.
Symptoms
- hesitation or flat spots when accelerating
- reduced power, sometimes limp mode
- rough idle or stalling
- black smoke on diesels
- engine warning light
Likely causes, most likely first
| No. | Cause |
|---|---|
| 01 | contaminated MAF element |
| 02 | intake leak after the MAF |
| 03 | EGR valve stuck open (diesels) |
| 04 | blocked air filter |
| 05 | oiled or incorrect aftermarket intake |
What to check, step by step
- 01Check the air filter and intake ducting for blockage or leaks between the MAF and the engine
- 02Compare the MAF reading in live data with the expected value at idle and at full load
- 03On diesels, check that the EGR valve closes fully: an open EGR valve lowers fresh air flow through the MAF
- 04Clean the MAF only if its maker permits it; otherwise replace a confirmed faulty sensor without touching the element.
- 05Remove any oiled aftermarket filter that may contaminate the sensor