how to fix misfire code P0301 on my Volvo XC90 Second Generation (2015-2024)

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the engine is cool before starting work.
• Disconnect the negative battery terminal to prevent electrical shock.

2. Inspect and Replace Spark Plug

• Sub-steps:
  1. Remove the engine cover if necessary.
  2. Disconnect the ignition coil connector from cylinder 1.
  3. Remove the ignition coil by unscrewing the retaining bolt and pulling it out.
  4. Extract the spark plug using a spark plug socket.
  5. Inspect the spark plug for wear; replace it if the electrode is worn or if there is heavy fouling.
  6. Install a new spark plug, ensuring the gap is set to manufacturer specifications (0.028 to 0.031 inches).
  7. Reinstall the ignition coil and reconnect the connector.

3. Inspect and Replace Ignition Coil

• Sub-steps:
  1. If the spark plug is not the issue, remove the ignition coil again.
  2. Inspect the coil for cracks or signs of arcing.
  3. Replace the ignition coil with a new unit if damage is found.
  4. Reinstall the ignition coil and reconnect the electrical connector.

4. Check Fuel Injector

• Sub-steps:
  1. Disconnect the fuel injector connector on cylinder 1.
  2. Use a noid light to check if the injector is receiving a signal while cranking the engine.
  3. If no signal is detected, inspect the wiring and the Engine Control Unit (ECU) for faults.
  4. If the injector is not functioning, replace it with a new injector.

5. Compression Test

• Sub-steps:
  1. Remove the spark plug from cylinder 1.
  2. Insert a compression gauge into the spark plug hole.
  3. Crank the engine and record the compression reading.
  4. Compare the reading to the manufacturer’s specifications (typically around 150-200 psi).
  5. If compression is low, further investigation into the engine internals may be necessary.