what does the P0303 code indicate for my Toyota Highlander Third Generation (2014-2019)

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. Inspect and Replace Ignition Components

• Spark Plug Replacement

  • Remove the ignition coil cover if necessary.
  • Disconnect the ignition coil connector and remove the ignition coil.
  • Remove the spark plug using a spark plug socket.
  • Inspect the spark plug for wear; replace with a new spark plug if necessary (use OEM specifications for gap).
  • Reinstall the new spark plug and ignition coil.

• Ignition Coil Replacement (if faulty)

  • If the ignition coil shows signs of failure during inspection, replace it.
  • Ensure proper seating and reattach the electrical connector.

3. Fuel Injector Service

• Fuel Injector Cleaning or Replacement
  • If the fuel injector is clogged, consider using a fuel injector cleaner or replacing it.
  • To replace, disconnect the fuel lines and electrical connectors.
  • Remove the old injector and install the new one, ensuring proper seating and connection of electrical connectors.

4. Compression Test (if necessary)

• If misfire persists, perform a compression test on cylinder 3.
  • Remove the spark plug from cylinder 3.
  • Insert the compression tester into the spark plug hole.
  • Crank the engine to obtain a compression reading. Compare to manufacturer specifications.

5. Final Assembly

• Reinstall any removed components, ensuring all connections are secure.
• Reconnect the battery terminal.