what does it mean when my Toyota Corolla E170 (2013-2019) shows P0303 code?

Learn how to diagnose and fix P0303 cylinder 3 misfire in Toyota Corolla E170 (2013-2019). Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shock.

2. Inspect and Replace Spark Plug

• Tools Required: Socket wrench, spark plug socket, torque wrench.
• Remove the ignition coil cover if applicable.
• Disconnect the ignition coil connector for cylinder 3.
• Remove the ignition coil by unbolting and pulling it out.
• Remove the spark plug using a spark plug socket.
• Inspect the spark plug for wear; replace if necessary.
• Install a new spark plug (torque to manufacturer specifications, typically around 13 lb-ft).
• Reinstall the ignition coil and reconnect the connector.

3. Inspect and Replace Ignition Coil

• If the spark plug appears fine, test the ignition coil using a multimeter (check resistance specifications).
• If faulty, remove the ignition coil and replace it with a new one.
• Reconnect the ignition coil connector and ensure it is seated correctly.

4. Check Fuel Injector

• If misfire persists, remove the fuel injector from cylinder 3.
• Inspect for clogs and test the injector's spray pattern using a fuel injector tester.
• Replace the injector if it is malfunctioning.

5. Compression Test

• If the misfire continues, perform a compression test on cylinder 3.
• If compression is below specifications, further engine repairs may be needed (e.g., head gasket, valve issues).