VOLVO
CEM-B103C83 - Left Headlamp Control. Bus Signal / Message Failures. Value of signal protection calculation incorrect
System
Central Electronic Module (CEM)
Volvo models this fault code applies to
Applies to the following models:
2 modelsV40 (2013–), V40 Cross Country (2013–)
Show models by year and engine (2)
What does this fault code mean?
The central electronic module (CEM) and the left main headlamp control unit (LHCU) exchange data over the LIN bus. The fault code is stored when the data from the LHCU is incorrect, which can make the headlamp adjustment wrong.
Possible causes
- Contact resistance, oxidation or loose connections in connectors or joints
- Damaged left main headlamp control unit (LHCU)
What you can do
- 1Check the connectors and wiring to the left headlamp for oxidation, looseness and contact resistance, and gently move them with the ignition on
- 2With a diagnostic tool, look for other fault codes ending in 86 or 88 in the control unit; they point to the bus and should be dealt with first
- 3Clear the fault code and road test. If it returns, have a workshop check the control unit with diagnostic equipment
- 4After the repair, check that the headlamp side and height adjustment works, and have a workshop adjust the headlamp if needed
Symptoms you may notice3
- Headlamp side adjustment does not follow the steering wheel correctly, or does not work
- Headlamp height adjustment is wrong or does not work
- Main beam with automatic high beam control does not work
What the fault can affect2
- The light range is used as a fixed setting
- Side adjustment stops in the straight-ahead position
General guidance for car owners. Diagnosis on the car can point to a different cause.