VOLVO
ECM-0325 - Knock sensor. Faulty signal
System
Engine Control Module (ECM)
Volvo models this fault code applies to
Applies to the following models:
5 modelsC30 (2007–2013), S40 (1996–2004), S40 (2004–2013), V40 (1996–2004), V50 (2004–2013)
Show models by year and engine (16)
- Volvo C30 (2007–2013)2007–2009Engine B4164S3, B4184S11, B4184S8, B4204S3 only
- Volvo C30 (2007–2013)2010Engine B4164S3, B4184S11, B4184S8, B4204S3, B4204S4 only
- Volvo C30 (2007–2013)2011–2012Engine B4164S3, B4204S3, B4204S4 only
- Volvo C30 (2007–2013)2013Engine B4204S3, B4204S4 only
- Volvo S40 (1996–2004)2001–2004Engine B4184SJ only
- Volvo S40 (2004–2013)2005Engine B4164S3, B4184S11 only
- Volvo S40 (2004–2013)2006Engine B4164S3, B4184S11, B4184S8 only
- Volvo S40 (2004–2013)2007–2009Engine B4164S3, B4184S11, B4184S8, B4204S3 only
- Volvo S40 (2004–2013)2010Engine B4164S3, B4184S11, B4184S8, B4204S3, B4204S4 only
- Volvo S40 (2004–2013)2011–2012Engine B4164S3, B4204S3, B4204S4 only
- Volvo V40 (1996–2004)2001–2004Engine B4184SJ only
- Volvo V50 (2004–2013)2005Engine B4164S3, B4184S11 only
- Volvo V50 (2004–2013)2006Engine B4164S3, B4184S11, B4184S8 only
- Volvo V50 (2004–2013)2007–2009Engine B4164S3, B4184S11, B4184S8, B4204S3 only
- Volvo V50 (2004–2013)2010Engine B4164S3, B4184S11, B4184S8, B4204S3, B4204S4 only
- Volvo V50 (2004–2013)2011–2012Engine B4164S3, B4204S3, B4204S4 only
What does this fault code mean?
The engine control module (ECM) either receives no signal from the knock sensor when engine speed and load are above a certain level, or receives a signal the control module cannot rely on. The knock sensor detects when combustion becomes irregular. The fault is checked with the engine running and while driving, and it may be noticed as knocking from the engine.
Possible causes
- Contact resistance in the connectors
- Knock sensor installed loosely
- Open circuit or short to ground or voltage in the signal wire from the knock sensor
- Open circuit in the ground wire or ground wire shorted to voltage
- Defective or damaged knock sensor
What you can do
- 1Read out the fault code, erase it and road-test to see whether it returns
- 2Switch off the ignition and check that the knock sensor is firmly fitted. If the car has more than one knock sensor, the front one is the main one to check
- 3Check the connectors to the knock sensor and the control module for contact resistance and oxidation
- 4Use a multimeter to check that the signal wire from the knock sensor has no open circuit and is not shorted to ground or voltage
- 5If you have a diagnostic tool, check in live data that the knock sensor signal appears during a road test, also under load and not only at idle
- 6If no fault is found in the wiring, the knock sensor is the likely cause. Have a workshop confirm this before you replace it
Symptoms you may notice2
- The malfunction indicator lamp (MIL) is lit
- The engine may knock
General guidance for car owners. Diagnosis on the car can point to a different cause.