Charge air pressure sensor
Check the charge air pressure sensor, coolant temperature sensor, charge air temperature sensor, fuel supply pressure sensor and fan speed sensor, along with the connectors and electrical cables in the circuit. Check that the intake system is not blocked by for example ice or debris.Also check that the air bellows are OK and that they are not squeezed together. 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 pressure sensor, coolant temperature sensor, charge air temperature sensor, fuel supply pressure sensor or 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.The maximum engine torque is limited by approximately 40 % as long as the fault is active. The engine also responds more slowly than normal to throttle actuation. This is because the smoke limiter is not operating correctly. 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 controlAn 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 above the permitted level.
Possible causes:- Open 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.