P0304

Alldata Editor Note:

Volvo does not provide information regarding DTC P0304 for some models.
However, it has been reported that various Volvo engine control modules will produce this code. The code is associated with cylinder misfire [cyl #4] and causes increased emissions which may cause three-way catalytic converter (TWC) damage.

Possible Causes
- Defective spark plugs, ignition cables, ignition coil or flywheel/pulse wheel
- Blocked/leaking injector
- Uneven compression
- Leakage between the cooling system and cylinders
- Moisture, flashover in the ignition system on HT side
- Intermittent open-circuit, intermittent short-circuit to ground, intermittent short-circuit to voltage supply, contact resistance or loose connection in the ignition system low-tension side, in the injector circuit or fuel pump (FP) circuit
- Fuel stoppage
- Water in the spark plug wells
- Contaminated fuel or incorrect fuel type
- Repeated cold starting where the engine coolant temperature (ECT) has not reached normal operating temperature between starts.

Manufacture codes associated with this P code may include ECM-44, ECM-45, ECM-4D.