Share a caseSign in
Air intakeSeverity Medium: diagnose soon

P0101Mass or Volume Air Flow "A" Circuit Range/Performance

What it means

The MAF reading works electrically but doesn't match what the ECU expects for the engine speed, load and throttle. Either the sensor misreports, or air is entering after it.

Symptoms

  • Hesitation or flat spots when accelerating
  • Rough idle or stalling
  • Higher fuel consumption
  • On diesels: limp mode, sometimes black smoke

Common causes

  • Contaminated or failing MAF sensor
  • Air leak between the MAF and the engine (intake hose, intercooler pipe)
  • Blocked air filter
  • EGR valve stuck open (diesel)

What to check first

  1. Compare MAF g/s (or mg/stroke) with the expected value for engine size and rpm
  2. Smoke-test the intake tract after the MAF
  3. Check MAF supply, ground and signal with a scope
Can I drive with P0101? Usually yes for a short distance, but performance or economy may suffer and the fault can get worse. Diagnose it soon.
Practise it: Dirty MAF sensor in the engine simulator shows this fault in live data, tests and on the scope.Open in the simulator

Generic OBD-II meaning. Manufacturer-specific meanings and checks can differ; always check the service information for the car.

How to test the parts behind P0101

Mass air flow sensor (MAF)Wiring, typical values, multimeter and scope tests

Known engine problems that set P0101

1.9 TDI PD: Air mass meter (MAF) reading lowVolkswagen, Audi, Skoda, Seat, Ford · typically 100,000–250,000 km

Cases with P0101 (0)

Share yours

No published cases with this code yet.

Colleagues asking about P0101

Ask for help

Stuck on P0101? Describe what you measured and ask the community.

P0101: questions and answers

What does P0101 mean?

P0101: Mass or Volume Air Flow "A" Circuit Range/Performance. The MAF reading works electrically but doesn't match what the ECU expects for the engine speed, load and throttle. Either the sensor misreports, or air is entering after it.

What are the symptoms of P0101?

Hesitation or flat spots when accelerating. Rough idle or stalling. Higher fuel consumption. On diesels: limp mode, sometimes black smoke.

What causes P0101?

Contaminated or failing MAF sensor. Air leak between the MAF and the engine (intake hose, intercooler pipe). Blocked air filter. EGR valve stuck open (diesel).

How do you diagnose P0101?

1. Compare MAF g/s (or mg/stroke) with the expected value for engine size and rpm 2. Smoke-test the intake tract after the MAF 3. Check MAF supply, ground and signal with a scope

Can I drive with P0101?

Usually yes for a short distance, but performance or economy may suffer and the fault can get worse. Diagnose it soon.