how to fix P0303 code in my Toyota Highlander Third Generation (2014-2019)?

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, multimeter, compression tester, torque wrench, basic hand tools.
• Safety Warnings: Disconnect the battery before starting any electrical work.

2. Spark Plug Replacement

1. Remove the engine cover (if applicable) using a socket set.
2. Disconnect the ignition coil connector from cylinder 3.
3. Remove the ignition coil by unscrewing the retaining bolts.
4. Remove the spark plug using a spark plug socket; inspect for wear or damage.
5. Check and adjust the spark plug gap according to manufacturer specifications (typically around 0.043 inches for Toyota).
6. Install the new spark plug, ensuring it is torqued to the manufacturer’s specifications (typically around 13 lb-ft).
7. Reinstall the ignition coil and connect the electrical connector.

3. Ignition Coil Testing/Replacement

1. Use a multimeter to test the resistance of the ignition coil (consult service manual for specifications).
2. If the ignition coil is out of spec, replace it with a new one.
3. Install the new ignition coil, ensuring it is seated properly and secured with screws.

4. Fuel Injector Cleaning/Replacement

1. If the injector is suspected to be clogged, remove it from the engine.
2. Clean the fuel injector using a fuel injector cleaning kit or replace it if necessary.
3. Reinstall the fuel injector and reconnect any electrical connectors.

5. Compression Testing

1. Remove all spark plugs to facilitate easier cranking.
2. Insert the compression tester into the spark plug hole of cylinder 3.
3. Crank the engine for about 5-10 seconds and record the compression reading.
4. Compare the reading to manufacturer specifications; if it is below spec, further engine diagnostics may be required.