how to fix the P0303 code on my Toyota Corolla E210 (2019-2024)?

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

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool before starting work.

2. Replace Spark Plug and Ignition Coil (if faulty)

• Tools Required: Socket set, torque wrench, spark plug socket, dielectric grease.
• Remove the engine cover (if applicable) using the socket set.
• Disconnect the electrical connector from the ignition coil on cylinder 3.
• Remove the ignition coil using the socket set and inspect for damage.
• Replace the spark plug in cylinder 3 with a new one, ensuring it is gapped correctly per manufacturer specifications (typically around 0.044 inches).
• Install the new ignition coil, applying dielectric grease to the boot before connection.
• Reconnect the electrical connector and replace the engine cover.

3. Clean or Replace Fuel Injector (if faulty)

• Tools Required: Fuel injector removal tool, cleaning solvent or new fuel injector.
• Disconnect the fuel lines and electrical connector from the fuel injector on cylinder 3.
• Remove the fuel injector using the removal tool.
• If cleaning, soak the injector in a cleaning solvent and use compressed air to clean it thoroughly.
• If replacing, install the new injector with a new O-ring lubricated with engine oil.
• Reconnect the fuel lines and electrical connector.

4. Compression Test (if necessary)

• Tools Required: Compression tester.
• Remove the spark plug from cylinder 3.
• Insert the compression tester into the spark plug hole.
• Crank the engine a few times and record the pressure reading.
• Compare the reading to the manufacturer’s specifications for normal compression (typically around 180-200 psi).
• If compression is low, further investigation into internal engine issues may be necessary.