Communication with the SCR control unit
Clear the fault code memory and try to start the engine.Switch the power off and on several times with the starter keyIf the fault code is regenerated, check the electrical cables and clean the connectors.If the fault code is still generated, check that both the SCR control unit and NOx sensor upstream of the catalytic converter are receiving voltage from U15 at the same time.If no fault is found, renew the NOx sensor for the catalytic converter first and then the SCR control unit, (if the vehicle is fitted with one).
What you'll see
No driver-visible symptom recorded.
System reaction
No system-reaction text recorded.
Diagnostic depth
The CAN message MSG8 "NOx sensor data before catalytic converter" is not received from the NOx sensor. If the vehicle is configured with an SCR system, this message is received via the SCR control unit.
Communication between the engine control unit and the NOx sensor before the catalytic converter has been interrupted.On vehicles with an SCR system the message is sent via the SCR control unit. If fault code 100C is generated at the same time, there is probably a fault in the communication between the engine control unit and the SCR control unit. See description of fault code 100C.If the vehicle is equipped with an SCR system and fault code 100C is not generated at the same time, there is probably a fault in the communication between the SCR control unit and the NOx sensor before the catalytic converter.If the fault code has only been generated once, this may be because the voltage to the NOx sensor has been interrupted while the SCR control unit has been supplied with voltage. If the fault code is frequently generated, this is probably due to problems with electrical cables or loose connections.