my Toyota Highlander XU70 (2020-Present) has a P0301 code, how do I fix it

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Ensure the engine is cool to avoid burns.

2. Inspect and Replace Spark Plug

• Remove the ignition coil for cylinder 1:
  • Unplug the electrical connector.
  • Remove the mounting bolts using a socket set.
• Extract the spark plug using a spark plug socket:
  • Inspect for signs of wear, such as carbon buildup or damage.
  • Replace with a new spark plug if necessary, ensuring proper gap (usually 0.043 inches for most Toyota models).
  • Torque the new spark plug to the manufacturer's specification (typically 13 ft-lbs).

3. Check and Replace Ignition Coil

• If the spark plug is in good condition, inspect the ignition coil:
  • Use a multimeter to measure the resistance of the ignition coil.
  • If out of specification, replace the ignition coil with a new one.
• Reinstall the ignition coil and reconnect the electrical connector.

4. Test Fuel Injector Operation

• Remove the fuel injector connector for cylinder 1.
• Use a noid light or multimeter to check for signals to the injector.
• If there’s no signal, further investigate wiring or ECU issues.
• If the injector is faulty, replace it with a new one, ensuring proper seating and connection.

5. Compression Test

• If misfire persists, conduct a compression test on cylinder 1:
  • Remove the spark plug and connect a compression gauge.
  • Crank the engine for a few seconds to obtain a reading.
  • Compare the results with specifications (usually around 150-200 psi).
• If compression is low, further engine diagnostics may be necessary.