how to fix P0301 misfire code in Toyota Corolla E170 (2013-2019)

Solution

1. Preparation

• Gather the 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

• Remove the ignition coil for cylinder 1:
  • Disconnect the electrical connector.
  • Unscrew the mounting bolts and lift off the coil.
• Remove the spark plug:
  • Use a spark plug socket and ratchet to unscrew and remove the spark plug.
• Inspect the spark plug for wear or fouling; replace if necessary:
  • If replacing, gap the new spark plug according to manufacturer specifications (typically around 0.043 inches).
• Install the new spark plug and torque to specification (typically 13 lb-ft).
• Reinstall the ignition coil and reconnect the electrical connector.

3. Inspect and Replace Ignition Coil (if necessary)

• If the ignition coil appears damaged or if the spark plug was fouled, replace the ignition coil:
  • Remove the faulty ignition coil as described above.
  • Install the new ignition coil in reverse order, ensuring it is seated properly.
  • Reconnect the electrical connector.

4. Check Fuel Injector

• If misfire persists, inspect the fuel injector for cylinder 1:
  • Disconnect the fuel injector connector.
  • Use a noid light to check for signal; if no signal, further diagnostics on the ECM may be required.
  • If the injector is faulty, remove and replace:
    • Disconnect the fuel line carefully to prevent spills.
    • Unscrew the mounting and lift out the injector.
    • Install the new injector and reconnect the fuel line and electrical connector.

5. Perform Compression Test (if needed)

• If misfire continues, perform a compression test:
  • Remove the spark plugs from all cylinders.
  • Insert the compression gauge into cylinder 1 and crank the engine.
  • Compare the readings with manufacturer's specifications.
  • Low compression may require further inspection of valves or piston rings.