how to troubleshoot P0301 code on Toyota Highlander Third Generation (2014-2019)

Solution

1. Preparation

• Gather tools and parts needed.
• Disconnect the negative battery terminal to ensure safety.

2. Inspect and Replace Spark Plug

• Using a socket set, remove the ignition coil for cylinder 1.
• Remove the spark plug using a spark plug socket.
• Inspect the spark plug for wear and replace it if necessary (use OEM replacement with correct gap).
• Reinstall the spark plug and ignition coil.

3. Test and Replace Ignition Coil (if necessary)

• Use a multimeter to check the resistance of the ignition coil (refer to specifications in the repair manual).
• If the ignition coil is out of specs, remove it and replace it with a new one.
• Reinstall the ignition coil and reconnect all electrical connections.

4. Clean or Replace Fuel Injector

• If the fuel injector appears dirty, use a fuel injector cleaner or cleaner kit to clean it.
• If necessary, remove the fuel injector using the appropriate tools, and replace it with a new one.
• Reinstall the fuel injector and ensure connections are secure.

5. Perform Compression Test (if misfire persists)

• Remove the spark plug again and connect the compression tester to the spark plug hole.
• Crank the engine to record compression readings. Compare with manufacturer specifications.
• If compression is low, further investigation may be needed, which could involve checking for valve issues or head gasket failure.