P0101 — Mass Air Flow Circuit Range/Performance
Moderate severityWhat it means
P0101 is stored when the engine control unit sees a fault involving the mass air flow (MAF) sensor signal. The MAF sensor measures how much air enters the engine, and the control unit uses it to set the fuel quantity, so a bad MAF signal upsets the whole air–fuel mixture. A “range/performance” fault means the value is present but implausible — it does not agree with other sensors or expected conditions.
Common symptoms
- Readings that drift or disagree with related sensors
- Hesitation, stalling or lack of power
- Black smoke or rough idle
- Higher fuel consumption
Likely causes
- Drifting, contaminated or aged sensor
- A mechanical issue skewing the reading
- Dirty or contaminated MAF sensing element
- An air leak before or after the MAF sensor
What to check first
- Cross-check the reading against related sensors in live data on a cold start
- Compare the g/s airflow reading at idle with expected values in live data
- Clean the MAF element with dedicated MAF cleaner only
Can you keep driving?
Usually drivable with reduced performance, but poor fuelling can foul the spark plugs and catalytic converter — diagnose soon.
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