how to fix a P0301 code on my Toyota Corolla E210 (2019-2024)

Solution

1. Preparation

• Gather tools: OBD-II scanner, socket set, compression tester, multimeter, spark plug socket, torque wrench.
• Disconnect the battery to ensure safety while working on electrical components.

2. Inspect Spark Plug

• Remove Engine Cover: If applicable, remove any covers to access the spark plug.
• Remove Spark Plug: Use a spark plug socket to carefully unscrew and remove the spark plug from cylinder 1.
• Inspect Condition: Check for excessive carbon buildup, cracks, or worn electrodes. Replace if necessary.

3. Check Ignition Coil

• Disconnect Ignition Coil: Unplug the electrical connector from the ignition coil on cylinder 1.
• Test Coil Resistance: Use a multimeter to check primary and secondary resistance. Compare readings against manufacturer specifications.
• Replace Coil if Faulty: If the coil is out of specification, replace it with a new one.

4. Perform Compression Test

• Remove Spark Plug Again: If not already done, remove the spark plug from cylinder 1.
• Insert Compression Tester: Screw the compression tester into the spark plug hole.
• Crank Engine: Turn the engine over several times to get an accurate reading.
• Evaluate Results: Compare the compression value with the manufacturer's specifications. If low, further engine diagnostics may be needed.

5. Inspect Fuel Injector

• Remove Fuel Rail: Disconnect the fuel rail to access the injector for cylinder 1.
• Inspect Injector: Check for clogs or leaks. Use a cleaning solution if necessary to clean the injector.
• Test Injector Function: If available, use a noid light or oscilloscope to check for proper electrical signal to the injector.

6. Address Vacuum Leaks

• Visual Inspection: Check hoses and gaskets for signs of wear or damage.
• Spray Test: Use a spray (such as carb cleaner) around the intake manifold while the engine is running to identify leaks.
• Repair Any Leaks: Replace any damaged hoses or gaskets as necessary.