Charge air temperature sensor
Check that coolant and charge air are approximately the same temperature when the engine is cold.Check the charge air temperature sensor, coolant temperature sensor, charge air pressure sensor, fuel supply pressure sensor and fan speed sensor, along with the connectors and electrical cables in the circuit.Proceed as follows to verify that the fault has been rectified:Start the engine and run it at idling speed for at least 15 seconds. If the fault has been rectified, the fault code becomes inactive. Clear the fault code. Switch the power off and on with the starter key three times in succession at 10 second intervals to extinguish the warning lamp.
What you'll see
No driver-visible symptom recorded.
System reaction
There is a common power supply for the charge air temperature sensor, coolant temperature sensor, charge air pressure sensor, fuel supply pressure sensor and fan speed sensor. If a fault occurs in one of the sensors, this can affect the circuits of the other sensors.If the voltage is outside the permitted range, the control unit uses a preprogrammed value.For engines with EGR, the engine runs with EGR but without any feedback from the mass flow sensor. The control unit will therefore only roughly control the EGR content using the predefined values on the EGR damper position. Calibration of the mass flow sensor is switched off.The fault affects the vehicle's emissions of nitrogen oxides (NOx) and the lamp which warns about a high level of contaminants comes on in the instrument cluster. A text message is also displayed on vehicles with NOx control.Vehicles with NOx control An active fault code limits the maximum engine torque by approximately 40% after the engine has been running for 50 hours.An active fault code cannot be deleted from the control unit. When the fault has been rectified, the control unit must verify that the fault has been rectified in order for the fault code to become inactive.
Diagnostic depth
The voltage in the circuit has been below the permitted level.
Possible causes:- Short circuit in charge air pressure sensor circuit. - Fault in the circuit of the coolant temperature sensor, charge air temperature sensor, fuel supply pressure sensor or fan speed sensor.