The exhaust gas temperature required for burning off the diesel particulates of at least 550 … 600 ยฐC is detected by the exhaust gas temperature sensors and transmitted to the PCM.
The exhaust gas temperature input parameters are used for calculation purposes by the PCM, which also takes other parameters into account.
Depending on the exhaust gas temperature calculated, the PCM decides whether or not the regeneration process can be initiated.
Effects of faults
In the case of a fault at one of the two exhaust gas temperature sensors, the value of the other exhaust gas temperature sensor is used by the PCM and a substitute value is calculated.
Diagnosis
The monitoring system checks:
โข the sensor for short circuit to ground/battery and open control loop.
โข The logical rise/fall rate of the signal, whereby intermittent faults are detected (e.g. loose connector contacts),
โข for plausibility,