how to fix my Toyota Highlander Third Generation (2014-2019) with a P0301 code

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the vehicle battery to prevent electrical shorts.
• Allow the engine to cool before starting work.

2. Inspect and Replace Spark Plug

• Tools Required: Socket set, spark plug socket, torque wrench, dielectric grease.
• Remove the ignition coil from cylinder 1 by unbolting it and disconnecting the electrical connector.
• Remove the spark plug using a spark plug socket.
• Inspect the spark plug for wear; replace if necessary.
• Apply dielectric grease to the new spark plug threads and install it, torquing it to the manufacturer’s specifications (typically around 13-15 lb-ft).
• Re-install the ignition coil and reconnect the electrical connector.

3. Inspect and Replace Ignition Coil (if needed)

• If the spark plug is in good condition, check the ignition coil for cracks or carbon tracking.
• Tools Required: Socket set.
• Remove the ignition coil from cylinder 1.
• Install the new ignition coil, ensuring it is seated correctly, and reconnect the electrical connector.

4. Check and Replace Fuel Injector (if needed)

• Disconnect the fuel injector connector for cylinder 1.
• Remove the fuel rail to access the injector.
• Tools Required: Socket set, fuel line removal tool.
• Remove the faulty injector and replace it with a new one.
• Reinstall the fuel rail and reconnect all necessary connectors.

5. Perform Compression Test

• If issues persist, perform a compression test on cylinder 1.
• Tools Required: Compression tester.
• Remove the spark plug and insert the compression tester in its place.
• Crank the engine and record the compression reading; it should match manufacturer specifications (typically around 180-200 psi).
• If compression is low, further investigation into the piston rings, valves, or head gasket may be necessary.