VOLVO
ECM-0303 - Misfire cylinder 3.Signal too high
System
Engine Control Module (ECM)
Volvo models this fault code applies to
This fault code has different meanings depending on model, model year or engine. Select the meaning that applies to your car.
Applies to the following models:
3 modelsC30 (2007–2013), S40 (2004–2013), V50 (2004–2013)
Show models by year and engine (14)
- 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 (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 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) counts misfires in cylinder 3 and stores the fault when the count exceeds what is allowed while driving. The cylinder is then not burning its fuel completely, which gives a rough running engine and reduced power. The fault should be corrected, since unburnt fuel can damage the catalytic converter.
Possible causes
- Blocked or leaking injector for cylinder 3
- Fault in the EGR system
- Uneven compression in cylinder 3
- Air leakage in the intake system
- Faulty fuel pressure or damaged fuel pipes
- Faulty ignition system or contaminated fuel
What you can do
- 1Read out the fault code, erase it and road-test to see whether it comes back
- 2Check the fuel level in the tank and that the engine oil level is correct
- 3High-voltage ignition parts: keep clear while the engine runs. Check the cylinder 3 spark plug wells for moisture and damaged plug insulation
- 4Look for air leaks in hoses and the intake pipe, especially at the connections
- 5If you have a diagnostic tool, check in live data how the misfire counter for cylinder 3 behaves at idle compared with the other cylinders
- 6If the fault remains, have a workshop with diagnostic equipment measure the fuel pressure and compression and check the injector for cylinder 3
Symptoms you may notice4
- The malfunction indicator lamp (MIL) is lit
- The engine misfires and does not fire on all cylinders
- The engine is difficult to start
- Poor performance and uneven idle
General guidance for car owners. Diagnosis on the car can point to a different cause.