how to resolve P0300 misfire code on Honda Accord Eleventh Generation (2023-present)?

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, multimeter, compression tester, fuel pressure gauge.
• Ensure the vehicle is parked on a level surface and the engine is off. Disconnect the battery's negative terminal to ensure safety while working on electrical systems.

2. Inspect Ignition Components

• Sub-steps:
  1. Remove the engine cover (if equipped) using a socket set.
  2. Disconnect the wiring harness from each ignition coil.
  3. Remove the ignition coils and inspect them for cracks or carbon tracking.
  4. Remove and inspect the spark plugs for wear, carbon build-up, or improper gap. Replace if necessary.
  5. Reinstall new or inspected ignition components and reconnect the wiring harness.

3. Check Fuel System

• Sub-steps:
  1. Connect the fuel pressure gauge to the fuel rail.
  2. Turn the ignition key to the "On" position (do not start the engine) and check for proper fuel pressure as per specifications in the service manual.
  3. If pressure is low, inspect the fuel pump, fuel filter, and fuel injectors for blockages or failures.
  4. Clean or replace fuel injectors as required.

4. Inspect for Vacuum Leaks

• Sub-steps:
  1. Visually inspect all vacuum lines and hoses for cracks or disconnections.
  2. Use a smoke machine or carburetor cleaner to detect any leaks while the engine is idling.
  3. Replace any damaged hoses and ensure all connections are secure.

5. Check Engine Compression

• Sub-steps:
  1. Remove the spark plugs to access the cylinders.
  2. Insert the compression tester into the spark plug hole of each cylinder.
  3. Crank the engine and record the compression readings for each cylinder.
  4. Compare the readings; if any cylinder is significantly lower than the others, further investigation may be needed (e.g., valve issues, head gasket failure).