my Toyota Camry XV70 (2018-2024) has a check engine light with code P0301

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a flat surface, and the engine is cool.
• Disconnect the battery to prevent any electrical shorts.

2. Inspect and Replace Spark Plug

• Tools Required: Socket set, torque wrench, spark plug socket.
• Remove the ignition coil cover if applicable.
• Disconnect the electrical connector from the ignition coil of cylinder 1.
• Remove the ignition coil using the socket set.
• Remove the spark plug using the spark plug socket.
• Inspect the spark plug for wear (color, gap, and carbon build-up).
• Replace with a new spark plug if damaged; torque to manufacturer specifications (typically around 13 lb-ft or 18 Nm).

3. Inspect and Replace Ignition Coil

• If the spark plug is in good condition, inspect the ignition coil.
• Tools Required: Socket set.
• Remove the ignition coil from cylinder 1.
• Inspect for cracks or carbon tracking.
• Replace with a new ignition coil if necessary.

4. Check Fuel Injector

• If misfire persists, inspect the fuel injector for cylinder 1.
• Tools Required: Multimeter, fuel injector cleaning kit (optional).
• Disconnect the injector connector.
• Test the injector resistance with a multimeter; compare with specifications (usually around 12-16 ohms).
• If faulty, replace the fuel injector.

5. Compression Test

• If all else fails, perform a compression test.
• Tools Required: Compression tester.
• Remove the spark plug and insert the compression tester into cylinder 1.
• Crank the engine and observe the pressure reading; compare with manufacturer specifications (usually 150-200 psi).
• If compression is low, further inspect the valves or piston rings.