Temperature sensor before compressor low or ambient temperature sensor high
Compare the temperature between the ambient temperature sensors (AAT1, AAT2 and T202/T126) Check the wiring and the connectors to the ambient temperature sensor (AAT1) Change the ambient temperature sensor (AAT1) To verify the repair run the vehicle above 30km/h for 2 minutes.
What you'll see
No driver-visible symptom recorded.
System reaction
The system may shut off the EGR system at low measure ambient temperatures if the engine is equipped with EGR system.
Diagnostic depth
The ambient temperature (AAT1) is higher compared to the other ambient temperature sensor (AAT2) and to the temperature sensor in the air inlet (T202 or T126).
The ambient temperature sensor (AAT1) is faulty ot the sensor has been exposed to unusually high temperature compared with the other temperature sensors.