Error Code P0303: Misfire Detected in Cylinder No. 3
What does this mean?
Diagnostic code P0303 is a generic Powertrain code, meaning it applies to all vehicles equipped with an OBD-II system. Although the code is standardized, specific repair steps may vary depending on the vehicle’s make and model.
Simply put, a P0303 code indicates that your car’s engine control computer has detected a malfunction in one of the engine’s cylinders. In this specific case, the problem is located in cylinder number 3. This means the cylinder is not functioning correctly, resulting in a misfire.
Possible Symptoms
A misfire in cylinder No. 3 can manifest through various symptoms, including:
- Difficulty starting the engine.
- The engine may misfire, shake, or hesitate during operation.
- Other symptoms may also be present depending on the underlying cause.
Potential Causes
Several factors can cause a P0303 code. Here is a list of the most common causes:
- Faulty Ignition Components:
- Faulty spark plug.
- Damaged or faulty spark plug wire.
- Faulty ignition coil (or coil pack).
- Fuel Supply Problems:
- Faulty fuel injector for cylinder No. 3.
- Lack of fuel (low level, faulty fuel pump, clogged fuel filter).
- Air and Exhaust Related Problems:
- Faulty oxygen sensor(s).
- Burnt exhaust valve.
- Faulty catalytic converter.
- Engine Mechanical Problems:
- Poor compression in cylinder No. 3.
- Electronic Problems:
- Faulty Engine Control Unit (ECU) (rare).
Possible Solutions and Diagnostic Steps
When faced with a P0303 code, here are some troubleshooting and repair avenues:
- Resetting the code: If no symptoms are apparent, the first simple step is to reset the error code and observe if it reappears.
- Inspecting ignition components: If symptoms such as misfires or hesitation are present, carefully examine the wires and connectors related to the cylinders, especially those for cylinder No. 3.
- Preventive maintenance: If the ignition components (spark plugs, wires, distributor, and rotor if applicable) are old, it may be wise to replace them as part of your vehicle’s regular maintenance.
- Checking ignition coils: Test the operation of the ignition coil associated with cylinder No. 3 (or the coil pack).
- Checking the catalytic converter: If you smell rotten eggs from the exhaust, the catalytic converter might be faulty and require replacement.
- Inspecting fuel injectors: In some cases, a faulty fuel injector may be the cause of the problem.