Automatic Air RECIRCULATION Control Sensor: Notes

The sensor for automatic air recirculation control (AUC sensor) is secured on the microfilter compartment.

The automatic air recirculation control sensor evaluates the concentration of carbon monoxide and nitrogen oxides in the intake fresh air. If the automatic air recirculation control sensor has an emission level that is too high, then the integrated automatic heating/air conditioning system control unit (IHKA control unit) in the air recirculation function is automatically switched to (prerequisite: IHKA in the automatic mode).

Because of the lack of a fresh-air supply, air-recirculation mode is only available for a limited period of time. When the engine is started and the AUC function activated, fresh air is always selected for approx. 40 seconds due to the warming phase of the AUC sensor.