P0303 is triggered when a misfire is detected in the engine cylinder #4, meaning that the combustion cycle was incomplete. This DTC is stored when the ECU module in the car identifies a ≥2% increase or decrease in the rotational speed of the car crankshaft. Misfiring is often caused by low pressure levels, a loss of compression, timing problems, or spark plug malfunctions.
Possible causesIt means that the fourth cylinder of the engine is misfiring.
It is often triggered when parts of the ignition system are defective. For example, when there is an electrical fault, sparks aren’t forming properly , or the ignition coil has burnt out. It may also be the result of a rich air-fuel mixture, timing problems caused by worn components or a lack of synchronisation, or sensor malfunctions.
Driving the vehicle in this condition is advised against as it can become difficult to control and the engine could fail. If the fuel doesn’t combust properly, it passes through the exhaust system, burning outside of the cylinder and causing key parts to overheat. Misfires should be dealt with immediately to prevent further internal damage.
Fault code P0304 - Cylinder 4 Misfire Detected can occur with any car but is most often found on the following cars:
If you get the code P0304 on your car, make sure that the diagnostics are carried out correctly and the error is still relevant. Check for symptoms associated with the problem and explore options for resolving it.
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