how to fix P0301 code in Toyota Corolla E140 (2006-2013)

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the negative terminal of the battery to avoid electrical shock.
• Allow the engine to cool down before beginning work.

2. Replace Spark Plug

• Tools Required: Socket set, torque wrench, spark plug socket, gap gauge.
• Remove the engine cover if necessary.
• Disconnect the ignition coil connector from cylinder 1.
• Unscrew and remove the ignition coil with a socket.
• Remove the spark plug using a spark plug socket.
• Inspect and replace with a new spark plug, ensuring proper gap (0.043 inches or 1.1 mm).
• Reinstall the ignition coil and reconnect the connector.

3. Replace Ignition Coil (if needed)

• If the ignition coil was found faulty during diagnostics, proceed with replacement.
• Tools Required: Socket set, torque wrench.
• Follow the same steps as above to remove and replace the ignition coil.
• Ensure to torque the ignition coil mounting bolts to manufacturer specifications (usually around 7 ft-lbs).

4. Clean/Replace Fuel Injector (if needed)

• If the fuel injector is clogged or faulty, it may need cleaning or replacement.
• Tools Required: Fuel injector cleaning kit or new fuel injector, socket set.
• Disconnect the fuel injector wiring and fuel line (ensure to relieve fuel pressure first).
• Remove the old fuel injector and install the new one or clean it using the appropriate method.
• Reconnect the fuel line and wiring.

5. Check Compression

• If misfire persists after replacing spark plug and coil, perform a compression test.
• Tools Required: Compression gauge.
• Remove spark plugs from all cylinders.
• Insert the compression gauge into the cylinder 1 spark plug hole.
• Crank the engine a few times and record the compression reading.
• Compare with specifications (typically around 180 psi for a healthy engine).