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Mercedes-Benz C Class W204 2007 – 2009V looses power randomly and will not restart when switched off

POSTED 27 November 2022

Mercedes-Benz C Class W204 2007 – 2009V looses power randomly and will not restart when switched off

CDI-D OM646.8-- engine 4 cyl diesel

Symptoms

  • After a short drive, the engine MIL and ESP lights turn on the instrument cluster.
  • There is no throttle response.
  • The engine will crank but not restart.
  • If left to cool down for a while, the engine will restart
  • Occasional misfire/rev limit at various engine rpm
  •  

Fault code P2088 Check sensor voltage 1 stored.

 

Possible Causes

Rail pressure sensor wiring chaffing/rubbing against aluminium thermostat housing, causing the 5v sensor supply voltage circuit to short and lose power to the following components:

       B37 accelerator pedal sensor 1

       B37 accelerator pedal sensor 2

       B4/6 rail pressure sensor

       B6/1 camshaft hall sensor

 

Repair Steps

  1. Remove engine cover to gain access to B4/6 fuel rail pressure sensor.
  2. Locate damaged wiring and reposition away from thermostat housing / secure with a cable tie so wiring is now situated over existing wiring and not over the thermostat.
Before      

Merc1

After

Merc2           

  1. Refit engine cover and erase fault codes.
  2. Road test vehicle to verify repair.

       B6/1 camshaft hall sensor