What does fault code CEM-B1A9904 mean?

Diagnostic fault code details for CEM-B1A9904 (Volvo S60 (2011–), Volvo S80 (2007–), Volvo V60 (2011–)). Repair service at OBD Tuning.

VOLVO

CEM-B1A9904 - Power on reset. General Failure Information. System Internal Failures

System

Central Electronic Module (CEM)

Volvo models this fault code applies to

Applies to the following models:

7 models

S60 (2011–), S80 (2007–), V60 (2011–), V60 Cross Country (2015–), V70 (2008–), XC60 (2009–), XC70 (2008–)

Show models by year and engine (7)

What does this fault code mean?

The CEM checks its own internal components when the ignition is switched on. The fault code is set if any of them does not work, and the cause is faulty software in the CEM.

Possible causes

Faulty software in the CEM

What you can do

1Check that the battery has sufficient voltage
2Have a workshop reload the CEM with the latest software, then check the fault code
3Clear the fault code, start the car and see whether it returns
4If the fault remains after the reload, have a workshop replace the CEM

Symptoms you may notice1

The engine does not start

General guidance for car owners. Diagnosis on the car can point to a different cause.