how to diagnose P0301 misfire code on Toyota Tacoma N300 (2016-Present)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to ensure safety during repairs.

2. Inspect and Replace Spark Plug and Ignition Coil

• Remove the ignition coil and spark plug from cylinder 1.
  • Tools Required: Socket set, spark plug socket, ratchet.
  • Safety Warning: Ensure the engine is cool before working on spark plugs to avoid burns.
• Inspect the spark plug for wear, oil fouling, or carbon buildup. Replace if necessary.
• Test the ignition coil's resistance with a multimeter. Replace if it is out of specification.

3. Check and Repair Wiring

• Visually inspect the wiring harness connected to the ignition coil and fuel injector for any damage or corrosion.
• Repair or replace any damaged wiring or connectors found during inspection.

4. Compression Test

• Perform a compression test on cylinder 1.
  • Tools Required: Compression gauge.
• If compression is low (below manufacturer specifications), further investigate potential issues such as valve problems or head gasket failure.

5. Fuel Injector Testing and Replacement

• If the ignition coil is functioning properly, test the fuel injector for cylinder 1.
• If the injector is faulty (no signal or improper operation), replace the fuel injector.
  • Tools Required: Fuel injector removal tool (if necessary).

6. Reassemble and Clear Codes

• Reinstall spark plug, ignition coil, and any other components removed during the process.
• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the trouble codes.