VOLVO
CEM-3F91 - Fuel pump relay. Short-circuit to supply voltage
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 CEM checks the fuel pump relay, which sits inside the CEM. The fault is set if the fuel pump output is shorted to supply voltage, or if the supply wire has a break or the pump is not connected. Older cars with a CEM up to model year 2006 can also have an internal ground path damaged by a short.
Possible causes
- The supply wire to the fuel pump is shorted to supply voltage
- A break in the supply wire to the fuel pump, or the pump is not connected
What you can do
- 1Do not connect the fuel pump or any outside supply without first unplugging the CEM connector. An internal ground path in the CEM can otherwise break
- 2Use a multimeter to check that the wire to the fuel pump has no short to supply voltage or break
- 3Check that the fuel pump is connected and that the connectors are clean and tight
- 4If the fault remains after checking the wire, have a workshop check the CEM, since a short to supply voltage can damage it
- 5After the work, clear the code and check that it does not return
Symptoms you may notice1
- The battery discharges
General guidance for car owners. Diagnosis on the car can point to a different cause.