VOLVO
CEM-5A00 - Sun sensor. Signal too high
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 reads the sun sensor. If the signal is too high, the code is set. The cabin temperature then does not drop in strong sunlight, because the control module uses a substitute value for solar load.
Possible causes
- The sun sensor wire is shorted to supply voltage
- A damaged sun sensor
What you can do
- 1With the ignition on, vary the light on the sun sensor and watch its signal. Cover the sensor with your hand, then shine a torch on it from close range
- 2If the sensor does not react to light, use a multimeter to check that the signal wire is not shorted to supply voltage
- 3Check that the connectors at the sun sensor and the CEM are seated and not corroded
- 4After the work, clear the code and check that the cabin cools when the sun shines
Symptoms you may notice1
- Cabin temperature does not fall in strong sun
What the fault can affect1
- The control module uses a substitute value for solar load, roughly the maximum
General guidance for car owners. Diagnosis on the car can point to a different cause.