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How do you fix a P0301?

Published on April 10th, 2022

P0301 is an error code that indicates a misfire in cylinder 1. This can happen for a variety of reasons, including a faulty spark plug, a dirty air filter, or a problem with the fuel injector. If the problem is not fixed, it can lead to engine damage.

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1. Replace the spark plugs and wires

  1. Remove the hood and front fascia of the car.
  2. Disconnect the negative battery cable.
  3. Remove the four screws that hold the coil pack cover in place.
  4. Remove the coil pack cover.
  5. Remove the spark plugs and wires.
  6. Replace the spark plugs and wires.
  7. reconnect the battery cable.
  8. Replace the coil pack cover.
  9. Restore the screws that hold the coil pack cover in place.

2. Check the ignition coil

  1. Remove the battery cable.
  2. Disconnect the negative battery cable.
  3. Remove the spark plugs.
  4. Remove the coil cover.
  5. Check for fouled or damaged coils. Replace any damaged or fouled coils.
  6. Reattach the spark plugs and battery cable.
  7. Test the engine by starting it and then turning it off and on.

3. Clean the fuel injectors

  1. Remove the air filter.
  2. Remove the fuel injectors.
  3. Clean the injectors with a solvent and a brush.
  4. Reinstall the fuel injectors.
  5. Replace the air filter.
  6. Replace the fuel cap.

4. Check the engine compression

  1. Park the car in a secure location with the engine off.
  2. Remove the air cleaner assembly.
  3. Remove the spark plugs.
  4. Compress the engine oil to 30 psi.
  5. Check the compression on each cylinder.
  6. Replace the spark plugs, air cleaner assembly, and engine oil if necessary.

5. Check for vacuum leaks

  1. Check for any vacuum leaks on the air bag system.
  2. Replace the air bag if necessary.
  3. Reconnect the vacuum hoses.
  4. Reinstall the air bag.

If you didn't find success with an option above, then try:

  1. Replace the fuel filter.
  2. Check the oxygen sensor.
  3. Adjust the idle speed.