how to fix P0303 code on my Toyota RAV4 XA50 (2019-2024)

Solution

1. Preparation

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

2. Inspect and Replace Spark Plug

1. Remove the engine cover if applicable.
2. Disconnect the ignition coil connector for cylinder 3.
3. Unbolt and remove the ignition coil from cylinder 3 using a socket set.
4. Remove the spark plug using a spark plug socket and ratchet.
5. Inspect the spark plug for wear or damage; replace it if needed with a new spark plug that meets OEM specifications.
6. Reinstall the spark plug and torque it to the manufacturer's specification (typically around 13-16 lb-ft).
7. Reattach the ignition coil and connector.

3. Test and Replace Ignition Coil (if necessary)

1. If the spark plug was in good condition, test the ignition coil using a multimeter. Measure the resistance across the primary and secondary terminals.
2. If the ignition coil is faulty (outside specified resistance), replace it with a new coil.
3. Reinstall the new ignition coil and reconnect the electrical connector.

4. Check Fuel Injector

1. Remove the fuel rail to access the fuel injector for cylinder 3.
2. Inspect the injector for clogs or leaks.
3. If necessary, replace the fuel injector with a new one.
4. Reinstall the fuel rail ensuring all connections are secure.

5. Compression Test (if misfire persists)

1. Remove the spark plug from cylinder 3 again.
2. Insert a compression gauge into the spark plug hole.
3. Crank the engine and note the compression reading.
4. If compression is low, further investigation into mechanical issues (valve, piston, head gasket) is required.