VOLVO
ECM-688D - By-pass valve intercooler. Signal missing
System
Engine Control Module (ECM)
Volvo models this fault code applies to
Applies to the following models:
3 modelsC30 (2007–2013), S40 (2004–2013), V50 (2004–2013)
What does this fault code mean?
The engine control module (ECM) monitors the charge air cooler bypass valve and how it works. If the module registers a fault in the PWM signal between itself and the bypass valve, the code is set, and it can also be set if the temperature in the output stage for the bypass valve becomes too high.
Possible causes
- Loose connection, contact resistance or oxidation in the terminals
- Open circuit in the power supply
- Open circuit in the signal wire
- Damaged bypass valve
- The bypass valve binds or has jammed, which can cause the output stage to overheat
What you can do
- 1Check the plug at the ECM and at the bypass valve for loose contact, contact resistance and oxidation
- 2With the ignition off and the connector disconnected, use a multimeter to check that the supply and signal wires are intact
- 3Check that the bypass valve has no visible damage or dirt that could make it bind
- 4Read the code, clear it and road test the car; if the code returns, have a workshop replace the bypass valve
Symptoms you may notice1
- Check engine lamp lit or behaving abnormally
General guidance for car owners. Diagnosis on the car can point to a different cause.