VOLVO
CEM-8F08 - Engine control module (ECM). Signal too low
System
Central Electronic Module (CEM)
Volvo models this fault code applies to
Applies to the following models:
5 modelsS60 (2001–2009), S80 (1999–2006), V70 (2000–2008), V70 XC / XC70 (2001–2007), XC90 (2003–)
What does this fault code mean?
The central electronic module (CEM) controls both the wake-up line to the ECM and the hazard warning flashers from the same driver circuit. The code is set when the wake-up signal level to the ECM is too low, which points to the signal wire being shorted to ground.
Possible causes
- The wake-up signal wire to the ECM is shorted to ground
What you can do
- 1With diagnostic equipment, read the status of the wake-up signal to the ECM and check that it changes when the ignition position is switched from I to II
- 2Check that the connectors at the CEM and the engine control module are clean, firmly fitted and undamaged
- 3With the ignition off, use a multimeter to check that the signal wire has no contact with ground (the body)
- 4If the engine does not start although the starter turns, have a workshop with diagnostic equipment check the signal and the modules
Symptoms you may notice1
- The engine cranks but does not start
What the fault can affect1
- After repeated faults the output is switched off permanently until the code is cleared
General guidance for car owners. Diagnosis on the car can point to a different cause.