VOLVO
ECM-0300 - Misfire, at least one cylinder. 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 counts misfires across all cylinders together and logs a fault when the total exceeds a set limit. A misfire means combustion in a cylinder is missing or uneven, which shows as rough running and hard starting. The fault is not tied to one cylinder and can have many causes.
Possible causes
- Blocked or leaking fuel injector
- Fault in the EGR system, for example a sticking EGR valve
- Uneven or poor compression
- Air leak
- Incorrect fuel pressure
- Contaminated or incorrect fuel
What you can do
- 1Read the fault code, clear it and road test to see whether it returns
- 2Check that the engine oil is at the correct level on the dipstick
- 3Check that the air intake is sealed: listen for air leaks with the engine running
- 4Check the fuel level in the tank and ask whether the car was recently refuelled with wrong or contaminated fuel
- 5If you have a diagnostic tool, read the misfire count in live data at idle. A value clearly above normal points to misfires
- 6If the fault remains, have a workshop check the compression and the fuel system
Symptoms you may notice5
- Malfunction indicator lamp (MIL) lit
- Engine misfires
- Engine is difficult to start
- Poor performance
- Uneven idle
General guidance for car owners. Diagnosis on the car can point to a different cause.