how to address the P0300 code in my Toyota Highlander Fourth Generation (2020-present)

Solution

1. Preparation

• Gather tools and parts.
• Disconnect the battery to ensure safety.
• Allow the engine to cool if it has been running.

2. Inspect and Replace Spark Plugs

• Tools Required: Spark plug socket, ratchet, torque wrench.
• Remove the ignition coils by unbolting them and disconnecting the electrical connectors.
• Remove the spark plugs using a spark plug socket.
• Inspect the spark plugs for wear; replace if they are worn or fouled.
• Torque the new spark plugs to the manufacturer's specification (typically around 13-15 lb-ft).
• Reinstall the ignition coils and reconnect the electrical connectors.

3. Check and Replace Ignition Coils (if necessary)

• Tools Required: Socket set, torque wrench.
• Remove the ignition coils as previously described.
• Test each ignition coil with a multimeter for proper resistance; replace any faulty coils.
• Reinstall the new ignition coils and torque to specification (usually around 7-10 lb-ft).

4. Inspect Fuel System

• Tools Required: Fuel pressure gauge.
• Connect the fuel pressure gauge to the fuel rail’s service port.
• Turn the ignition on (do not start the engine) to check fuel pressure; it should match the specified range (consult the service manual).
• If pressure is low, inspect the fuel filter and fuel pump for issues. Replace as necessary.

5. Perform Compression Test

• Tools Required: Compression tester.
• Remove spark plugs and insert the compression tester into each cylinder.
• Crank the engine and record the compression readings.
• Compare readings to manufacturer specifications; if any cylinder is significantly lower, it may indicate a mechanical issue.