how to fix P0300 misfire code in Toyota Corolla E170 (2013-2019)

Solution

1. Preparation

• Gather 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 shock.

2. Inspect and Replace Spark Plugs

• Tools Required: Socket set, torque wrench, spark plug socket.
• Remove the ignition coil cover if applicable.
• Using the spark plug socket, remove each spark plug.
• Inspect the condition of the spark plugs; replace if worn or fouled.
• Install new spark plugs, ensuring a torque of 13 lb-ft (17 Nm).
• Reattach the ignition coil cover.

3. Test and Replace Ignition Coils (if necessary)

• Tools Required: Multimeter, socket set.
• Disconnect the electrical connector from each ignition coil.
• Use a multimeter to test the primary and secondary resistance of each coil.
• If a coil is out of specification, remove it using the socket set and replace with a new coil.
• Reconnect the electrical connectors.

4. Clean or Replace Fuel Injectors

• Tools Required: Fuel injector cleaning kit, fuel pressure gauge.
• Disconnect the fuel line from the injectors and relieve fuel pressure.
• If cleaning, use the injector cleaning kit per the manufacturer’s instructions; if replacing, remove the old injectors and install new ones.
• Reconnect the fuel line and check for leaks.

5. Check for Vacuum Leaks

• Tools Required: Smoke machine or carburetor cleaner.
• Start the engine and use a smoke machine around vacuum hoses to check for leaks.
• Alternatively, spray carburetor cleaner around hoses while the engine is idling and listen for RPM changes.
• Replace any damaged hoses.

6. Test Fuel Pressure

• Tools Required: Fuel pressure gauge.
• Connect the gauge to the fuel rail and turn the ignition to the "on" position (do not start).
• Check the fuel pressure against the specifications (typically 43-50 psi).
• If low, consider replacing the fuel pump or filter.