The MAF sensor works according to the hot film principle.
The sensor’s output signal is a digital square-wave signal with a variable frequency.
The following generally applies: the frequency drops with increasing engine speed.
The MAF sensor is used to control the exhaust gas recirculation (closed-loop control).
Effects of faults
In the event of a fault, the EGR system is switched off.
Diagnosis
The monitoring system checks:
• if the values output by the sensor are within the limits,
• the sensor for short circuit to battery/ground,
• for intermittent faults.
Emissions-related component:
• Yes (MIL-active).
