VOLVO
ECM-740B - Communication, central electronic module (CEM). Signal missing
System
Engine Control Module (ECM)
Volvo models this fault code applies to
Applies to the following models:
4 modelsC30 (2007–2013), C70 (2006–2013), S40 (2004–2013), V50 (2004–2013)
Show models by year and engine (9)
- Volvo C30 (2007–2013)2007Engine B5254T3 only
- Volvo C30 (2007–2013)2008–2013Engine B5254T7 only
- Volvo C70 (2006–2013)2006–2007Engine B5254T3 only
- Volvo C70 (2006–2013)2008–2013Engine B5254T7 only
- Volvo S40 (2004–2013)2005–2007Engine B5254T3 only
- Volvo S40 (2004–2013)2008Engine B5254T3, B5254T7 only
- Volvo S40 (2004–2013)2009–2012Engine B5254T7 only
- Volvo V50 (2004–2013)2005–2007Engine B5254T3 only
- Volvo V50 (2004–2013)2008–2012Engine B5254T7 only
What does this fault code mean?
The ECM has logged a problem on the CAN link between the CEM and the ECM. The fault may be caused by a broken or shorted CAN wire, or by an internal fault in the engine control module or in another module on the same part of the network. The fault applies to the C30, C70 (06-), S40 (04-) and V50.
Possible causes
- Open circuit in one of the CAN wires
- Short circuit between the CAN wires
- Internal fault in the engine control module
- Internal fault in another control module on the same part of the CAN network
What you can do
- 1First read the codes in the central electronic module and in other affected control modules, and remedy them
- 2Visually inspect the CAN wires to the engine control module for chafing, breaks and loose connectors
- 3Using a multimeter, check that the CAN wires are not shorted to each other or to ground
- 4Clear this code only after the other codes have been remedied and cleared, then road test the car
- 5If the fault remains, have a workshop with diagnostic equipment check the CAN network and the engine control module
Symptoms you may notice1
- No noticeable symptoms for the driver
General guidance for car owners. Diagnosis on the car can point to a different cause.