how to troubleshoot P0303 code in Toyota Highlander XU70 (2020-Present)

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the battery negative terminal to prevent electrical shorts.
• Allow the engine to cool before starting work.

2. Inspect and Replace Spark Plug

• Sub-steps:
  1. Remove the engine cover if applicable.
  2. Disconnect the ignition coil connector and remove the ignition coil from cylinder 3.
  3. Remove the spark plug using a spark plug socket.
  4. Inspect the spark plug for wear, carbon buildup, or damage. Replace if necessary.
  5. Install the new spark plug, ensuring it is torqued to the manufacturer’s specifications (usually around 13-15 lb-ft).
  6. Reinstall the ignition coil and reconnect the electrical connector.

3. Check and Replace Ignition Coil

• Sub-steps:
  1. If the spark plug is in good condition, test the ignition coil for proper operation using a multimeter.
  2. If the coil is faulty, remove it by unscrewing the mounting bolts and disconnecting the electrical connector.
  3. Install the new ignition coil, ensuring it is properly secured and connected.

4. Inspect Fuel Injector

• Sub-steps:
  1. Remove any necessary components to access the fuel injector for cylinder 3.
  2. Disconnect the fuel injector electrical connector.
  3. Perform a resistance test on the injector to check for continuity.
  4. If the injector is faulty, replace it by unscrewing it from the fuel rail and installing a new injector.
  5. Reconnect the electrical connector and any components removed.

5. Compression Test

• Sub-steps:
  1. Remove the spark plug from cylinder 3 again.
  2. Connect the compression tester to the spark plug hole.
  3. Crank the engine several times and record the compression reading.
  4. Compare the reading to the manufacturer’s specifications (usually around 170-210 PSI).
  5. If compression is low, further investigation into the engine internals is necessary.

Tools Required:

• OBD-II scanner
• Socket set
• Torque wrench
• Compression tester
• Multimeter
• Spark plug socket

Parts Required:

• Spark plug(s)
• Ignition coil (if faulty)
• Fuel injector (if faulty)

Estimated Repair Time: 2-4 hours

Safety Warnings:

• Disconnect the battery before working on electrical systems.
• Allow the engine to cool before opening components to prevent burns.