how to fix P0300 code in Toyota Highlander XU70 (2020-Present)

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical short circuits.

2. Replace Spark Plugs

• Sub-steps:
  1. Remove the engine cover if applicable.
  2. Carefully disconnect the ignition coil connectors and remove the ignition coils.
  3. Use a spark plug socket to remove the old spark plugs.
  4. Inspect the old spark plugs for wear; replace with new spark plugs according to manufacturer specifications (usually NGK or Denso).
  5. Torque the new spark plugs to the specified value (typically 13-16 lb-ft).
  6. Reinstall the ignition coils and reconnect the connectors.

3. Replace Ignition Coils (if needed)

• Sub-steps:
  1. If ignition coils are found faulty during inspection, remove them by unscrewing the mounting bolts.
  2. Install new ignition coils and ensure they fit snugly onto the spark plugs.
  3. Reconnect the wiring harness to each ignition coil.

4. Clean or Replace Fuel Injectors

• Sub-steps:
  1. If fuel injectors are not operating correctly, remove the fuel rail by unscrewing it from the engine.
  2. Disconnect the fuel lines carefully (use a rag to catch any fuel spills).
  3. Inspect and clean the fuel injectors using a specialized injector cleaning kit or replace them if significantly clogged or damaged.
  4. Reinstall the fuel rail and reconnect the fuel lines.

5. Conduct a Compression Test

• Sub-steps:
  1. Remove the spark plugs and install a compression gauge into the spark plug holes.
  2. Crank the engine several times and record the compression readings for each cylinder.
  3. If any cylinder shows low compression, further investigation may be required (valve issues, head gasket leaks).