how to fix the P0301 code on my Toyota Highlander Fourth Generation (2020-present)

Solution

1. Preparation

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

2. Replace Spark Plug

1. Remove the engine cover if necessary using a socket set.
2. Disconnect the ignition coil connector for cylinder 1.
3. Remove the ignition coil by unscrewing the bolts and pulling it out.
4. Use a spark plug socket to remove the spark plug from cylinder 1.
5. Inspect the old spark plug for signs of wear or damage.
6. Install a new spark plug (OEM recommended) and torque it to manufacturer specifications (usually around 13 lb-ft).
7. Reinstall the ignition coil and connect the electrical connector.

3. Test and Replace Ignition Coil (if necessary)

1. If the ignition coil was tested and found faulty, replace it with a new one.
2. Reconnect the ignition coil connector and ensure it is seated properly.

4. Inspect and Clean Fuel Injector

1. Remove the fuel injector from cylinder 1 by disconnecting the electrical connector and unscrewing the retaining clip.
2. Inspect the injector for carbon buildup; clean if necessary or replace with a new injector if faulty.
3. Reinstall the injector, ensuring it is properly seated and connected.

5. Compression Test (if needed)

1. If misfire persists, perform a compression test on cylinder 1.
2. Remove the spark plug and connect the compression tester.
3. Crank the engine and record the compression reading.
4. Compare with manufacturer specifications (typically around 180-200 psi); if low, further engine diagnostics may be needed.