1: Lack of power

2: Limp home mode

The computer noticed something wrong or lost contact with an important sensor that could ruin the engine or transmission and has de-rated the power so you can get home without the car stopping or damaging itself.

3: Engine Management light on

4: ECM fault codes

1: Faulty temperature sensors for catalytic converter and DPF

Temperature sensors for catalytic converter and DPF (Diesel Particulate Filter) on D52x4Tx engines may cease to function correctly. This will provide incorrect temperature readings to the ECM (Engine control module) resulting with MIL light on and car in limp home mode.

1: Check both Temperature sensor Data values

On the AssistPlus, go to 'TEMPERATURES', select 'EXHAUST'

2: Temperature sensor, catalytic converter (°C)

Measurement range: 0-1000 °C. This shows the current temperature upstream of the catalytic converter. Expected value when idling is between approx. 100 °C and 550 °C.

3: Temperature sensor, particle trap (°C)

Measurement range: 0-1000 °C. This shows the current temperature upstream of the particle trap. Expected value when the engine is idling is between approximately 100 °C and 500 °C.

4: Check for discrepancies

You are looking for a wide difference in temperature sensor values. This is best done with A+ connected to car and checking these values on a hot engine while driving. Both Temperature sensors should read approx the same with an excepted discrepancy of +/- 50 °C. If one temperature sensor is showing extremely high value, disconnect the sensors one at a time. Look for a change in the values to pin point which sensor is faulty.