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

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, compression tester, multimeter.
• Ensure the vehicle is parked on a level surface, and the engine is cool.
• Disconnect the battery negative terminal to prevent electrical shorts.

2. Inspect and Replace Spark Plug

1. Remove the engine cover if applicable.
2. Use the socket set to carefully remove the spark plug from cylinder 1.
3. Inspect the spark plug for signs of wear, fouling, or damage.
4. If necessary, replace the spark plug with a new one that meets OEM specifications (typically iridium).
5. Torque the new spark plug to the manufacturer's specified torque (usually around 13 ft-lbs for most Toyota models).

3. Inspect and Replace Ignition Coil

1. Disconnect the electrical connector from the ignition coil for cylinder 1.
2. Remove the ignition coil by unscrewing any retaining bolts.
3. Inspect the ignition coil for physical damage or corrosion.
4. If damaged, replace the ignition coil with a new one that meets OEM specifications.
5. Reinstall the ignition coil and reconnect the electrical connector.

4. Inspect Fuel Injector

1. Disconnect the fuel injector connector for cylinder 1.
2. Use a multimeter to test the injector's resistance; compare it against the manufacturer's specifications (usually between 12-16 ohms).
3. If the injector is faulty, replace it with a new one.
4. Reinstall the injector and reconnect the electrical connector.

5. Perform Compression Test

1. Remove the spark plug from cylinder 1.
2. Insert the compression tester into the spark plug hole.
3. Crank the engine for several seconds and record the compression reading.
4. Compare the reading to the manufacturer's specifications. If it's low, further investigation is needed into potential internal engine issues.