VOLVO
REM-DD21 - Tilt sensor or siren. Faulty signal
System
Rear Electronic Module (REM)
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 code is set when the rear electronic module (REM) registers a serious interference in its communication with the alarm's inclination sensor module (ISM) or siren (BBS), for example that communication is blocked. The alarm may give false alarms. Which of the two applies depends on when the car was built.
Possible causes
- Short-circuit between the signal cables
- Open circuit in one of the signal cables
- Internal fault in another control module on the same part of the network
What you can do
- 1Read and clear the code, road test the car and check whether it comes back
- 2With a multimeter, check that the signal cable to the inclination sensor or siren has no open circuit, no short to voltage and no contact with ground
- 3With the ignition off, check that the connector at the REM is fully seated and free from oxidation
- 4With diagnostic equipment, read the control modules on the network; if the inclination sensor or siren is missing there, the communication is probably broken
- 5If the cable is intact, replace the defective component or have a workshop determine which one it is
Symptoms you may notice1
- The alarm may give false alarms
General guidance for car owners. Diagnosis on the car can point to a different cause.