VOLVO
CEM-1A57 - Communication with the RTI module. Signal missing
System
Central Electronic Module (CEM)
Volvo models this fault code applies to
Applies to the following models:
4 modelsS60 (2001–2009), S80 (1999–2006), V70 (2000–2008), V70 XC / XC70 (2001–2007)
Show models by year and engine (4)
What does this fault code mean?
The central electronic module (CEM) has lost contact with the road traffic information module (RTI) and sets this code. If new software was recently loaded from a disc, the link may have dropped during the download, and then clearing the code is often enough. Otherwise it is a genuine communication fault, and the CEM should not be replaced.
Possible causes
- The RTI is not getting power
- The ground wire to the RTI is broken
- Contact resistance in the connections
- Broken CAN wiring to the RTI
- Wrong RTI for this car, for example a used module with different software or hardware
- New software was loaded into the RTI and the link dropped during the download
What you can do
- 1Insert and eject a DVD to see whether the RTI responds. A CD will eject but the system will not recognise it, so it only helps for the ejection check
- 2Check the RTI fuses. If one has blown, replace it once. If it blows again, use a multimeter to check the wire after it has no contact with ground.
- 3Check that the RTI connector is seated, not corroded, and that the cable to it is not chafed or pinched
- 4Check that the ground wire from the RTI to the body is tight and not broken. Use a multimeter if you are unsure
- 5After the work, clear the code and check that it does not return. If it does, read the module ID with a diagnostic tool if you have one
Symptoms you may notice3
- Traffic information is not shown or updated
- The RTI display does not raise
- The RTI is not working
General guidance for car owners. Diagnosis on the car can point to a different cause.