Air measurement · Fault code

P0101

Mass Air Flow Circuit Range / Performance

The airflow the MAF reports does not agree with what the ECU expects from the throttle, boost and rpm it can see.

Severity EXPERT Low — worth checking, not urgent
Driveability EXPERT Usually safe to drive while you diagnose
Tuning EXPERT Diagnose first — do not tune onto this A remap trusts the airflow signal; tuning on an implausible one puts the fuelling error into every load site.

Check first — in this order

The order is the product. A list of "possible causes" is what every parts site publishes, and it is why people replace parts blindly.

  1. Compare the airflow signal against calculated load and boost at the same operating points. This code means the two disagree; establishing how they disagree is the whole diagnosis. EXPERT
  2. Check for unmetered air after the sensor — a loose intake boot or a split pipe reads as a plausibility fault. EXPERT
  3. Check for restriction before it: a collapsed duct or a filter nobody has changed. EXPERT
  4. Inspect the sensor element for oil or dust contamination, common after an oiled aftermarket filter. EXPERT
  5. Check wiring and connector integrity, and the engine breathing path — crankcase ventilation and EGR flow both change what the sensor should be reading. EXPERT

What this code does not license you to replace

  • That the MAF sensor is dead. Range/performance means implausible, which is usually caused by something else in the air path.

Companion codes

Codes whose presence alongside P0101 changes the path.

P0299P0106P0171

Engines we cover that log this

EA888 Gen 3 Wastegated (petrol)VAG EA288 TDI Variable-geometry (diesel)
No workshop sign-off yet. The diagnostic order on this page has had a technical review of the knowledge model, performed by a model — not a manufacturer certification and not a mechanical inspection of any vehicle. No tuner has yet put their name to this ordering. Treat it as a reasoned starting point, confirm with measurement, and get a professional to sign off before you condemn a part.

Built by DMS Tuned

Stuck on P0101? Send us the log.

DMS Tuned is a real ECU-tuning shop. If you have a boost/requested-vs-actual log, run it through the analyser first — then message us and we will read it with you before you spend money on parts.

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