VOLVO
CEM-3A00 - ECM software. Faulty signal
System
Central Electronic Module (CEM)
Volvo models this fault code applies to
Applies to the following models:
5 modelsC30 (2007–2013), C30 Electric (2011–2013), C70 (2006–2013), S40 (2004–2013), V50 (2004–2013)
What does this fault code mean?
The CEM has registered faulty or altered engine control software (ECM). The fault can stop the engine from starting. It may be intermittent, and correct software is downloaded by a workshop.
Possible causes
- An incorrect software checksum
What you can do
- 1With the ignition on, check whether the code returns after switching the ignition off and on again
- 2Has the owner altered the engine software? Discuss it first, since a change that did not cause the fault should not be corrected
- 3Check that the battery terminals and cable connections are clean and tight, so the control modules get stable voltage
- 4Software is downloaded with diagnostic equipment and can only be done by a workshop
Symptoms you may notice1
- The engine does not start
General guidance for car owners. Diagnosis on the car can point to a different cause.