VOLVO
CEM-1A62 - Communication with the engine control module (ECM). Signal missing
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) has lost communication with the engine control module (ECM) and sets this code. The fault lies in the communication, not in the CEM, so the CEM should not be replaced. Without contact with the engine control module, the engine may stall, feel sluggish or fail to start even though the starter motor turns.
Possible causes
- The ECM is not getting power
- The ground wire to the ECM is broken
- Contact resistance in the connections
- Broken CAN wiring to the ECM
- Wrong ECM for this car, for example a used module with different software or hardware
- A common CAN network fault if several communication faults are stored at the same time
What you can do
- 1Check the ECM fuse. If it has blown, replace it once. If it blows again, use a multimeter to check the wire after it has no contact with ground.
- 2Check that the connectors to the engine control module are seated and free of corrosion, chafing or damage. Check that the ground point on the engine is clean and tight
- 3Use a multimeter to check the power supply and ground leads to the ECM for breaks. The fault may be intermittent if a lead has play
- 4Check first which engine variant the car has, since the signals differ between petrol and diesel engines
- 5After the work, clear the code, start the engine and check that the code does not return
Symptoms you may notice5
- The starter cranks but the engine will not start
- The engine stalls, including while driving
- The engine feels sluggish
- The malfunction indicator lamp (MIL) is lit
- A message appears in the display
General guidance for car owners. Diagnosis on the car can point to a different cause.