A position sensor is integrated in the EGR valve, which records the instantaneous position of the valve and reports it back to the PCM.
A position sensor is usually provided as follows.
• Emission standard III: Only in conjunction with a fixed turbocharger (no guide vane adjustment) – in this case, no MAF sensor is installed.
• Emission standard IV: In conjunction with a variable geometry turbocharger (electrically actuated guide vane adjustment). The position sensor, along with the MAF sensor, provides feedback on the quantity of recirculated exhaust gas.
Values
Reference voltage: 5 V
The position sensor in the EGR valve operates in a
voltage range from 0 to 5 V.
Effects of faults
Increased emissions of black smoke
The EGR system is switched off.
reduced engine power output
Diagnosis
The monitoring system checks:
• the sensor for short circuit to ground/battery and open control loop.
• logical rise/fall rates of the signal. The sliding contact is thus checked for faults (e.g. due to dirt). This type of malfunction can also indicate a loose connection (e.g. on the wiring harness connector).
• for plausibility: A seized or sticking EGR valve is detected in this manner.
