how to fix P0303 misfire code in my Toyota Corolla E140 (2006-2013)

Learn how to diagnose and fix P0303 cylinder 3 misfire in Toyota Corolla. Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the negative battery terminal to ensure safety while working on electrical components.

2. Replace Spark Plug

• Tools Required: Spark plug socket, ratchet, torque wrench.
• Remove the ignition coil for cylinder 3 by unscrewing the retaining bolts.
• Carefully pull the ignition coil out and set aside.
• Remove the spark plug using the spark plug socket and ratchet.
• Inspect the old spark plug and replace with a new one, ensuring it is gapped to manufacturer specifications (typically around 0.044 inches for Toyota).
• Torque the new spark plug to 13 lb-ft.

3. Inspect and Replace Ignition Coil

• Check the ignition coil for cylinder 3 for any visible damage or corrosion.
• If necessary, replace the ignition coil with a new one, ensuring proper seating and connection.
• Torque the ignition coil retaining bolts to the manufacturer’s specifications (typically around 8 lb-ft).

4. Inspect Fuel Injector

• Disconnect the electrical connector from the fuel injector for cylinder 3.
• Use a multimeter to check the injector's resistance (should typically be around 12-16 ohms).
• If the injector is faulty, replace it with a new one.
• Ensure the new injector is properly seated and reconnect the electrical connector.

5. Compression Test (if needed)

• If misfire persists, perform a compression test on cylinder 3 to ensure engine internals are functioning correctly.
• If compression is low, further investigation into the engine's internal components may be necessary.