P0100Powertrain
Powertrain · SAE
MAF Sensor Circuit Malfunction
Meaning
The ECU receives no signal or an irrational signal from the mass airflow (MAF) sensor. The hot-wire or hot-film sensing element cannot be validated. Without a reliable MAF measurement the ECU falls back to a degraded fuelling map.
Common causes
- Contaminated or failed hot-wire/hot-film sensing element (most common after high mileage or oiled-filter use)
- Open circuit or short in MAF wiring
- Corroded sensor connector
- Unmetered air leak downstream of MAF (cracked intake boot or hose)
- Sensor ground fault
Symptoms
- MIL illuminated
- Rough idle and poor acceleration
- Rich or lean fuel trims depending on failure mode
- Black smoke on diesel (excess fuel)
- Engine may run in limp mode
Severity
High severity: the engine runs on a degraded fuelling map; prolonged driving may damage the catalytic converter.
What to do
- Inspect the intake between MAF and throttle body for air leaks
- Check MAF wiring and connector
- Clean MAF sensing element with dedicated cleaner if dirty (petrol engines)
- Measure MAF output voltage/frequency at idle and compare to specification
- Replace MAF if values are out of range