how to fix P0301 code on my Toyota Highlander XU70 (2020-Present)

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, multimeter, compression tester, noid light, torque wrench, safety goggles, gloves.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Spark Plug

• Remove the ignition coil cover using a socket set.
• Disconnect the ignition coil connector from the spark plug.
• Remove the ignition coil from cylinder 1.
• Unscrew the spark plug using a socket wrench.
• Inspect the spark plug for wear and replace if needed (NGK or Denso recommended).
• Reinstall the spark plug, torquing to the manufacturer's specification (typically around 13 ft-lbs).
• Reattach the ignition coil and connector.

3. Test and Replace Ignition Coil (if necessary)

• Use a multimeter to test the primary and secondary resistance of the ignition coil. If outside recommended values, replace the ignition coil.
• Install a new ignition coil by reversing the removal process. Ensure proper connection of the electrical connector.

4. Inspect and Clean Fuel Injector

• If the ignition components are functioning, check the fuel injector for cylinder 1 using a noid light.
• If the light does not flash, replace the injector or clean it using an appropriate fuel injector cleaner.
• Reinstall the fuel injector if cleaned or replaced, ensuring proper seating and connection.

5. Compression Test (if misfire persists)

• Remove the spark plug from cylinder 1 again.
• Insert the compression tester into the spark plug hole.
• Crank the engine and record the compression reading. It should match manufacturer specifications (typically 150-200 psi).
• If the compression is low, further investigation into engine mechanical issues is required.

6. Final Steps

• Reconnect the negative battery terminal.
• Clear the codes with the OBD-II scanner and start the engine to check for any reoccurrences of the P0301 code.