how to fix P0303 code in Toyota Corolla E210 (2019-2024)

Learn how to diagnose and fix P0303 cylinder 3 misfire in Toyota Corolla E210 (2019-2024). Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather tools and parts necessary for the repair.
• Disconnect the negative battery terminal.
• Allow the engine to cool before working on it.

2. Replace the Spark Plug

• Tools Required: Socket set, torque wrench, spark plug gap gauge.
• Remove the engine cover (if applicable).
• Disconnect the ignition coil connector for cylinder 3.
• Remove the ignition coil bolt and carefully pull out the coil.
• Unscrew the old spark plug using a socket wrench.
• Inspect the spark plug for signs of wear; replace if necessary.
• Install the new spark plug, ensuring it is gapped correctly.
• Torque the spark plug to the manufacturer's specification (typically around 13 lb-ft).
• Reinstall the ignition coil and connect the electrical connector.

3. Inspect and Replace the Ignition Coil (if needed)

• If the spark plug appears fine but the misfire persists, proceed to check the ignition coil.
• Remove the ignition coil for cylinder 3 as described above.
• Test the ignition coil with a multimeter for proper resistance.
• If faulty, replace with a new ignition coil.
• Reinstall the ignition coil and reconnect the connector.

4. Check and Clean the Fuel Injector (if needed)

• Remove the fuel rail (if necessary) to access the fuel injector for cylinder 3.
• Disconnect the fuel line and electrical connector from the injector.
• Remove the injector and inspect it for clogs or damage.
• Clean the injector using a fuel injector cleaner or replace it if necessary.
• Reinstall the injector and reconnect all lines and connectors.

5. Perform Compression Test (if needed)

• If misfire persists after spark plug and ignition coil replacement, perform a compression test.
• Remove the spark plug and insert the compression tester into cylinder 3.
• Crank the engine and record the compression reading.
• Compare with manufacturer specifications; low compression may indicate internal engine issues.