Volvo S40 | V40 | V50 | C30 Body Control Module / CEM Module – SID803 ECU Immobiliser Synchronising Service

Volvo S40 | V40 | V50 | C30 Body Control Module / CEM Module – SID803 ECU Immobiliser Synchronising Service

How immobiliser works on Volvo S40 2004-2009, V50 2004-2009, C30: Immobiliser data (immo) on these cars are stored in the Central electric module (CEM) located in driver compartment fuse box. The CEM receives transponder key signal from immobiliser coil and if key data is correct it sends synchronisation signal to motor ECU. If transponder key is stored in CEM and synchronisation data CEM-ECU is correct, CEM permit to start the engine. The engine ECU is also synchronized with ABS computer ID. (Serial number) For SID803 ECU synchronisation you must also read ABS ID (you can read ABS ID with Launch X431, Diagun or other diagnostic tool by the OBD socket and write it to SID803. The most common problem on these cars is lost synchronization between the CEM-ECU after flat battery / jump starting. In the engine ECU you will have fault code of “No communication with immobiliser” and engine will crank but not start. Remove CEM+Engine ECU, write down the ABS serial number+send them to us for re-synchronising, your items will be returned re-synchronised ready for refitting+all working perfectly again. Please see above pictures for exactly what you need to send to us.