how to fix the P0301 code in my Toyota Highlander Third Generation (2014-2019)

Solution

1. Preparation

• Gather all necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative battery terminal to avoid electrical shorts.

2. Replace Spark Plug

• Tools Required: Socket set, spark plug socket, torque wrench.
• Remove the ignition coil by unscrewing the retaining bolts and disconnecting the electrical connector.
• Use a spark plug socket to remove the old spark plug from cylinder 1.
• Inspect the old spark plug for signs of oil or carbon buildup.
• Install a new spark plug, torquing it to the manufacturer’s specifications (typically 13-15 lb-ft).
• Reattach the ignition coil and reconnect the electrical connector.

3. Inspect and Replace Ignition Coil

• If the spark plug was not the issue, proceed to inspect the ignition coil.
• Remove the ignition coil from cylinder 1.
• Test the ignition coil with a multimeter to check its resistance (consult the service manual for specific resistance values).
• If the coil is faulty, replace it with a new one, ensuring it is properly seated and secured.

4. Check and Replace Fuel Injector

• If misfire persists, inspect the fuel injector for cylinder 1.
• Remove the fuel injector and check for clogs or damage.
• If necessary, clean or replace the fuel injector.
• Reinstall the injector and ensure all connections are secure.

5. Compression Test

• If all previous steps do not resolve the issue, perform a compression test on cylinder 1.
• Remove the spark plug and install the compression tester.
• Crank the engine and record the compression reading.
• Compare the results to the manufacturer's specifications. If compression is low, further investigation into the engine's internal components may be necessary.