P0303 Fault Code

Cylinder 3 Misfire Detected

• What does that mean?
• Symptoms
• Causes
• Solutions

The P0303 fault code indicates that the engine control module (ECM) has detected a misfire in cylinder 3. This misfire can lead to poor engine performance, increased emissions, and potential damage to the engine over time. It is crucial to address any misfire codes promptly to maintain engine efficiency and reliability.

What are the symptoms of the P0303 code?

Common symptoms associated with a P0303 code may include:

• Rough idle or engine shaking specifically when at idle.
• Loss of power or acceleration issues.
• Decreased fuel efficiency as the engine struggles to run smoothly.
• Unusual engine noises or vibrations.
• Check Engine Light (CEL) illumination with a specific misfire code.

What causes the P0303 code?

Several factors can cause a misfire in cylinder 3, including:

• Faulty spark plug or ignition coil specific to cylinder 3.
• Fuel delivery issues such as clogged fuel injectors.
• Vacuum leaks affecting the air-fuel mixture.
• Engine compression problems in cylinder 3 due to worn piston rings or a bad head gasket.
• Faulty engine sensors, such as the Mass Air Flow (MAF) sensor or the Engine Coolant Temperature (ECT) sensor.

How to fix P0303?

To resolve a P0303 code, follow these general steps:

• Inspect and replace the spark plug and ignition coil for cylinder 3 if they are found to be faulty.
• Check the fuel injector for cylinder 3 for clogs or malfunctions, and clean or replace as necessary.
• Look for vacuum leaks in hoses and gaskets that may influence the air-fuel mixture.
• Conduct a compression test on cylinder 3 to rule out internal engine issues, addressing any identified problems.
• Reset the ECM and check for reoccurrence of the fault code after repairs are completed.