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

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the negative terminal of the battery to avoid electrical shorts.
• Allow the engine to cool before starting work.

2. Inspect and Replace Spark Plug

• Tools Required: Socket set, torque wrench, gap tool.
• Remove the engine cover if necessary.
• Disconnect the ignition coil connector for cylinder 1.
• Remove the ignition coil using a socket.
• Remove the spark plug using a spark plug socket.
• Inspect the spark plug for wear or fouling; replace it if necessary.
• Ensure the new spark plug is gapped correctly (typically 0.028-0.032 inches for most models).
• Install the new spark plug and torque to the manufacturer’s specifications (usually around 13 lb-ft).
• Reinstall the ignition coil and connect the connector.

3. Check and Replace Ignition Coil

• If the spark plug is fine, swap the ignition coil from cylinder 1 with another cylinder (e.g., cylinder 2).
• Clear the codes and start the engine to see if the misfire follows the ignition coil to the new cylinder.
• If the misfire does move, replace the ignition coil for cylinder 1.

4. Inspect Fuel Injector

• If the ignition coil is functional, check the fuel injector for cylinder 1.
• Use a multimeter to test the fuel injector's resistance; it should be within the manufacturer’s specifications (usually around 12-16 ohms).
• If faulty, replace the fuel injector with a new one.

5. Compression Test

• If the misfire persists, perform a compression test on cylinder 1.
• Remove the spark plug and install a compression gauge.
• Crank the engine and record the compression reading; it should be within the manufacturer’s specifications (typically around 150-200 psi).
• If compression is low, further investigation is needed for potential valve or head gasket issues.