how to diagnose a P0301 misfire code in my Toyota Camry Eighth Generation (2018-present)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to ensure safety while working.

2. Inspect and Replace Spark Plug

• Tools Required: Socket set, torque wrench
• Remove the ignition coil for cylinder 1:
  1. Disconnect the electrical connector from the ignition coil.
  2. Remove the mounting bolts securing the coil.
  3. Gently pull the coil out of the spark plug well.
• Remove the spark plug:
  1. Use a spark plug socket to carefully unscrew the spark plug from cylinder 1.
  2. Inspect the spark plug for signs of wear or damage. Replace if necessary.
• Install a new spark plug:
  1. Apply anti-seize lubricant to the threads (if applicable).
  2. Torque the spark plug to the manufacturer’s specifications (typically around 13-16 lb-ft).
• Reinstall the ignition coil and secure it with its bolts and electrical connector.

3. Inspect and Replace Ignition Coil

• If the spark plug is fine, proceed to check the ignition coil:
  1. Test the ignition coil’s resistance using a multimeter (consult the specific resistance values for the vehicle).
  2. If the coil is faulty, replace it with a new one:
     • Install the new ignition coil where the old one was removed, ensuring it is seated properly.
     • Reconnect the electrical connector.

4. Check Fuel Injector

• If the ignition coil is functional, inspect the fuel injector:
  1. Disconnect the fuel injector connector.
  2. Perform a resistance test on the injector to ensure it is within specifications.
  3. If faulty, replace the injector:
     • Remove the old injector and install the new one, ensuring O-rings are lubricated and seated correctly.

5. Compression Test

• If the issue persists, conduct a compression test:
  1. Remove the spark plug for cylinder 1 and screw in the compression tester.
  2. Crank the engine and record the compression reading.
  3. Compare the reading with specifications. If low, further investigation may be needed into the engine internals.