how to fix P0301 misfire code in Toyota Highlander XU70 (2020-Present)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool before beginning work.

2. Inspect and Replace Spark Plug

• Tools Required: Socket set, spark plug socket, torque wrench.
• Remove the engine cover if necessary.
• Use the spark plug socket to remove the spark plug from cylinder 1.
• Inspect the spark plug for wear, carbon build-up, or damage.
• If the spark plug is worn or fouled, replace it with a new one, ensuring it is the correct type and gap.
• Torque the new spark plug to the manufacturer's specifications (typically 13-16 lb-ft).

3. Check and Replace Ignition Coil

• Tools Required: Socket set, torque wrench.
• Locate the ignition coil for cylinder 1.
• Disconnect the electrical connector from the ignition coil.
• Remove the mounting bolts from the ignition coil using the socket set.
• If testing, swap the coil with another cylinder to determine if the issue moves.
• If replacing, install the new ignition coil and torque to manufacturer specifications.

4. Fuel System Check

• Tools Required: Fuel pressure gauge.
• Connect the fuel pressure gauge to the fuel rail.
• Turn the ignition key to the "On" position (do not start the engine) to check fuel pressure.
• Compare readings with manufacturer specifications. If pressure is low, further investigate the fuel pump or filter.

5. Compression Test

• Tools Required: Compression tester.
• Remove the spark plug from cylinder 1.
• Insert the compression tester into the spark plug hole.
• Crank the engine to get a reading.
• Compare the compression reading to manufacturer specifications. If low, further diagnosis of internal engine components may be necessary.