what does it mean when my Toyota Corolla E210 (2019-2024) shows code P0301?

Solution

1. Preparation

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

2. Inspect and Replace Spark Plug

1. Remove the ignition coil cover (if applicable).
2. Disconnect the electrical connector from the ignition coil.
3. Remove the ignition coil by unscrewing the retaining bolts.
4. Remove the spark plug using a spark plug socket and ratchet.
5. Inspect the spark plug for wear or damage. Replace it if necessary with a new spark plug that meets OEM specifications (typically NGK or Denso for Toyota).
6. Reinstall the spark plug and torque it to the manufacturer's specifications (usually around 13-16 lb-ft).
7. Reinstall the ignition coil and reconnect the electrical connector.

3. Check and Replace Fuel Injector (if necessary)

1. Remove the intake manifold or any components obstructing access to the fuel injector if required.
2. Disconnect the fuel injector electrical connector.
3. Carefully remove the fuel injector from the fuel rail using a fuel injector puller or gentle prying.
4. Inspect the injector for clogs or damage. If faulty, replace it with a new injector that meets OEM specifications.
5. Reinstall the injector, ensuring proper alignment and sealing with new O-rings.
6. Reconnect the electrical connector.

4. Perform Compression Test

1. Remove the spark plug from cylinder 1.
2. Insert the compression gauge into the spark plug hole.
3. Crank the engine several times and record the compression reading.
4. Compare the reading to the manufacturer’s specifications (typically around 180-200 psi).
5. If compression is low, further engine diagnosis may be necessary (potential head gasket or valve issues).