P0101

OBD (II)

P0101

Hot-film mass air flow sensors (MAF) - signal implausible

Diagnostic conditions
- Battery voltage between 10 V and 16 V
- Engine running
- Relatively long drive in all load ranges

Possible fault cause
- Hot-film mass air flow sensor 1 and / or 2 faulty (setpoint voltage with stopped engine and ignition on = 0.9 to 1.1 V) --> see Actual values, Filter [[DME mass air flow]], [[Mass air flow 1 (sensor)]] + [[Mass air flow 2 (sensor)]]
- Throttle valve stiff or >>blocked<<
- Secondary air between hot-film mass air flow sensor and throttle valve (e.g. crack in hose)
- Throttle valve adjusting unit faulty
- Turbo only: Intake air temperature sensor faulty (in boost pressure sensor)
- Naturally aspirated engines only: Intake air temperature sensor faulty (in hot-film mass air flow sensor)
- DME faulty (pressure sensor for ambient air pressure)

Affected terminals
-

Diagnosis/fault finding

Hot-film mass air flow sensor






Boost pressure sensor






Hint:
- For this fault code, the intake system between the hot-film mass air flow sensors and the throttle valve is monitored.
- The pressure sensor for ambient air pressure is installed in the engine control unit.

Hint:
If the connector A is disconnected from the DME control unit and the ignition is switched on or was switched on, the fault >>DME control unit Timeout<< is entered in many control units.


Hint:
If the control unit connector A was disconnected from the BME during fault finding or if the power supply was interrupted elsewhere (battery, fuse), adaptation of the throttle valve adjusting unit must be performed.

Hint:
Both of the hot-film mass air flow sensors must be checked.

Hint:
- Adaptation >>RKAT<< is additive, remains unadapted at ± 0.0%
- Adaptation >>FRAU<< is multiplicative, remains unadapted at + 1.00