how to fix P0300 code on my Toyota Camry XV50 (2012-2017) for random misfires?

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, multimeter, fuel pressure gauge, compression tester.
• Disconnect the negative battery terminal to ensure safety.
• Gather replacement parts as necessary, like spark plugs, ignition coils, or fuel injectors.

2. Inspect and Replace Spark Plugs

• Sub-steps:
  1. Remove the engine cover if equipped.
  2. Disconnect the ignition coils from the spark plugs.
  3. Use a socket set to remove the spark plugs.
  4. Inspect the spark plugs for wear; replace if they are worn or fouled.
  5. Gap new spark plugs according to manufacturer specifications (usually around 0.043 inches).
  6. Install the new spark plugs and torque them to the manufacturer’s specified value (typically 13 ft-lbs).
  7. Reconnect the ignition coils.

3. Check and Replace Ignition Coils

• Sub-steps:
  1. Test each ignition coil with a multimeter for proper resistance (consult repair manual for specific resistance values).
  2. Replace any faulty ignition coils with new ones.
  3. Reconnect all ignition coils after replacement.

4. Inspect and Clean Fuel Injectors

• Sub-steps:
  1. Remove the fuel rail with injectors attached (ensure fuel pressure is relieved before removal).
  2. Inspect injectors for clogs; clean them using a fuel injector cleaning kit if necessary, or replace if significantly clogged.
  3. Reinstall the fuel rail and ensure all connections are secure.

5. Inspect Vacuum Hoses

• Sub-steps:
  1. Visually inspect all vacuum hoses for cracks, breaks, or loose connections.
  2. Replace any damaged hoses and ensure all connections are tight.

6. Test Fuel Pressure

• Sub-steps:
  1. Connect a fuel pressure gauge to the fuel rail.
  2. Turn the ignition to the "ON" position (do not start the engine) to check the pressure.
  3. Compare the reading with manufacturer specifications; replace the fuel pump if pressure is low.

7. Perform Compression Test

• Sub-steps:
  1. Remove the spark plugs.
  2. Insert the compression tester into the spark plug holes.
  3. Crank the engine and record the compression readings for each cylinder.
  4. If readings are below specifications, further engine diagnosis may be needed.