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

Solution

1. Preparation

• Gather tools and parts needed.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool before beginning work.

2. Inspect and Replace Spark Plug

• Tools Required: Socket set, torque wrench, spark plug socket
• Remove the ignition coil covering (if applicable) and disconnect the electrical connector from the ignition coil.
• Remove the ignition coil from cylinder 1.
• Unscrew the spark plug from cylinder 1 using the spark plug socket.
• Inspect the spark plug for wear and replace it if necessary. Install a new spark plug and torque it to the manufacturer's specification (typically around 13 lb-ft).
• Reinstall the ignition coil and reconnect the electrical connector.

3. Test and Replace Ignition Coil (if necessary)

• Tools Required: Multimeter (for resistance testing)
• If the spark plug is in good condition, test the ignition coil by measuring the primary and secondary resistance using a multimeter.
• If the readings are outside the manufacturer's specifications, replace the ignition coil with a new one.
• Reinstall the new ignition coil and ensure it is securely connected.

4. Inspect and Test Fuel Injector

• Tools Required: Fuel injector tester
• Disconnect the fuel injector harness for cylinder 1.
• Use a fuel injector tester to check the injector’s operation. If it does not operate, replace the fuel injector.
• Reconnect the injector harness after testing.

5. Conduct Compression Test

• Tools Required: Compression gauge
• Remove the spark plug from cylinder 1 and insert the compression gauge.
• Crank the engine and record the compression reading. Compare it to manufacturer specifications (usually around 140-200 psi).
• If the compression is low, further investigation into the cylinder head or piston rings may be needed.

6. Inspect for Vacuum Leaks

• Visually inspect hoses and gaskets for cracks or disconnections.
• Use a smoke machine or carburetor cleaner to test for leaks around the intake manifold and throttle body. Repair or replace any damaged components.