how do I fix the P0301 misfire code on my Toyota Corolla E170 (2013-2019)?

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to ensure safety.
• Allow the engine to cool before starting work.

2. Inspect and Replace Spark Plug

• Tools Required: Socket set, torque wrench, gap gauge.
• Remove the ignition coil by unscrewing the mounting bolts and disconnecting the electrical connector.
• Use a socket to remove the spark plug from cylinder 1.
• Inspect the spark plug for signs of wear or damage. If necessary, replace it with a new spark plug ensuring the gap is set to manufacturer specifications (typically around 0.043 inches for a Corolla).
• Reinstall the spark plug and torque it to the manufacturer’s specifications (usually around 13 lb-ft).
• Reinstall the ignition coil and connect the electrical connector.

3. Inspect and Replace Ignition Coil (if necessary)

• If the spark plug was in good condition but the misfire persists, proceed to inspect the ignition coil.
• Swap the ignition coil with another cylinder (e.g., cylinder 2).
• Clear the codes and start the engine to see if the misfire moves to the other cylinder. If it does, replace the ignition coil.

4. Inspect Fuel Injector (if necessary)

• If the ignition coil is functioning correctly, check the fuel injector for cylinder 1.
• Disconnect the electrical connector and remove the fuel injector.
• Clean or replace the fuel injector as needed.
• Reinstall the injector and reconnect the electrical connector.

5. Compression Test (if necessary)

• If misfire continues, perform a compression test on cylinder 1.
• Remove the spark plug and insert the compression tester into the cylinder.
• Crank the engine and record the compression reading; it should be within the manufacturer’s specifications (typically around 180 psi).
• If compression is low, further investigation of the cylinder’s internals (valves, piston rings) will be necessary.