P0101 Mass air flow sensor A range/performance
What P0101 means
The mass air flow sensor is working electrically, but its reading does not match the airflow the engine computer expects from throttle position, engine speed and manifold pressure. The computer then fuels the engine incorrectly.
P0101 is a generic SAE J2012 code: it means the same on every make. The exact cause still depends on the car, so read the freeze-frame data before replacing parts.
At a glance
- Severity
- High
- Typical repair cost
- 40–350 €
- Workshop time
- 0.3–1.5 h
- Repair difficulty
- Easy
- DIY possible
- Yes
- Check engine light
- Yes
- Affects emissions test
- Yes
Parts and labour at an independent workshop in Europe. Main dealers charge more; the cause decides the bill, not the code.
Symptoms
- Check engine light on
- Hesitation or flat spots when accelerating
- Rough idle or stalling
- Higher fuel consumption
- Black smoke on diesels
Common causes
- Dirty or contaminated MAF sensing element (dust, oil from an oiled air filter)
- Air leak between the MAF and the throttle body: cracked hose or loose clamp
- Clogged air filter or blocked intake
- Ageing or failed MAF sensor
- On diesels: EGR valve stuck open or a boost leak
Can I keep driving with P0101?
Have it checked within a few days. Start with cleaning the sensor, as a dirty MAF is a common cause and the wrong air reading affects fuelling and emissions.
What to check first
- Inspect the air filter and all intake ducting between the MAF and the engine for cracks and loose clamps.
- Clean the MAF sensing element with a dedicated MAF cleaner (never touch the element or use other solvents).
- Compare live MAF readings at idle and around 2,500 rpm with the expected values for the engine.
- On a diesel check the EGR valve for sticking and the boost system for leaks; replace the MAF sensor if readings stay wrong.
Related codes
- P0102 Mass air flow (MAF) sensor A circuit low
- P0100 Mass air flow sensor A circuit
- P0103 Mass air flow sensor A circuit high
- P0104 Mass air flow sensor A circuit intermittent
- P0105 Manifold absolute pressure / barometric pressure sensor circuit
- P0106 Manifold absolute pressure / barometric pressure sensor range/performance
- P0107 Manifold absolute pressure / barometric pressure sensor circuit low
- P0108 Manifold absolute pressure / barometric pressure sensor circuit high
Data: TORKO fault-code catalogue, built on OBDex (CC0-1.0) and reviewed against workshop practice. Informational only — it does not replace a diagnosis by a mechanic.
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