how to fix P0301 misfire code in Volvo XC90 First Generation (2002-2014)

Solution

1. Preparation

• Gather tools and parts required.
• Disconnect the negative battery terminal to ensure safety.
• Allow the engine to cool before proceeding.

2. Replace Spark Plug

• Remove the ignition coil cover, if necessary, using a socket set.
• Disconnect the wiring harness from the ignition coil on cylinder 1.
• Remove the ignition coil using a socket and extension.
• Unscrew and remove the spark plug from cylinder 1 using a spark plug socket.
• Install a new spark plug, ensuring the gap is set to the manufacturer's specification (typically around 0.028-0.032 inches).
• Reinstall the ignition coil, reconnect the wiring harness, and replace any covers.

3. Test and Replace Ignition Coil (if necessary)

• If the spark plug replacement does not resolve the issue, test the ignition coil using an ohmmeter.
• If the resistance is outside the manufacturer’s specifications, replace the ignition coil with a new one.
• Reinstall the coil back onto the spark plug and reconnect the wiring harness.

4. Check Fuel Injector

• If misfire persists, check the fuel injector for cylinder 1.
• Remove the fuel injector harness and use a multimeter to check if the injector is receiving power.
• If the injector is faulty, replace it by removing the fuel rail (ensure the fuel system is depressurized first).
• Install a new fuel injector, ensuring proper alignment and sealing.

5. Verify Repairs

• Reconnect the negative battery terminal.
• Start the engine and let it idle; check for smooth operation.
• Clear the P0301 code using the OBD-II scanner and perform a road test to confirm the misfire is resolved.