Autodata Technical Issue 15 – 2008 Mercedes C-Class 350 with several trouble codes won’t start
Each month the Autodata team answers a common technical question and provides a printable document with technical diagrams to download and keep, exclusively for IGA members. This month, a Mercedes C-Class 350 won’t start, has broken wipers, a brake lamp fault message and 4 trouble codes.
Q. We are having problems diagnosing a Mercedes C-Class C350 2008 which will not start. Also the front wipers are not working and there is a ‘brake lamp fault’ message in the instrument panel. There are trouble codes B21272, B215F72, B212171 stored. We have tested the battery and it is in good health. We have checked power supplies to the engine bay fuse box which are all ok. Has anyone seen this problem before?
A. The V6 petrol C-Class in 2008 demonstrated the symptoms you have described. It is due to defective relays, located in the engine bay fuse box/relay plate, for the ignition main circuits, secondary air pump and engine control (EC) Fig1.
The defective relays were fitted to vehicles in the following specific chassis range:
• 204****A064140 - 204****A158064
• 204****F057431 - 204****F162917
• 204****R004400 - 204****R029520
Replacing these relays should rectify the faults. Remember to erase the trouble codes.
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