how to fix P0300 misfire code in Toyota Corolla E170 (2013-2019)

Solution

1. Preparation

• Gather required tools and parts.
• Disconnect the battery to prevent electrical shorts during repairs.

2. Inspect and Replace Spark Plugs

• Tools Required: Socket set, torque wrench, spark plug socket, dielectric grease.
• Sub-steps:
  1. Remove the ignition coils by unscrewing the mounting bolts and disconnecting the electrical connectors.
  2. Use a socket to remove the spark plugs from the cylinder head.
  3. Inspect the condition of each spark plug; replace any that are worn or damaged.
  4. Gap new spark plugs according to manufacturer specifications.
  5. Apply a small amount of dielectric grease to the spark plug threads and install them, torquing to the manufacturer's specification (typically 13-15 lb-ft).
  6. Reinstall the ignition coils ensuring they are seated properly and reconnect the electrical connectors.

3. Inspect and Replace Ignition Coils

• Tools Required: Socket set, multimeter.
• Sub-steps:
  1. Use a multimeter to test the resistance of each ignition coil; compare results to specifications (typically around 0.5 - 0.7 ohms for primary resistance).
  2. If any coil is out of specification, replace it with a new one.
  3. Reinstall the coils and reconnect the connectors.

4. Check Fuel Injectors

• Tools Required: Fuel pressure gauge, injector cleaning kit (if needed).
• Sub-steps:
  1. Connect the fuel pressure gauge to the fuel rail and check for appropriate pressure (typically around 43-50 psi).
  2. If pressure is low, inspect the fuel pump and filter.
  3. If injectors are suspected of clogging, use an injector cleaning kit to clean them or replace if necessary.

5. Inspect Vacuum Lines and Intake

• Tools Required: Visual inspection tools.
• Sub-steps:
  1. Perform a visual inspection of all vacuum lines and intake manifold gaskets for cracks or leaks.
  2. Replace any damaged vacuum lines or gaskets.

6. Test Engine Compression

• Tools Required: Compression tester.
• Sub-steps:
  1. Remove all spark plugs to access the cylinders.
  2. Insert the compression tester into the first cylinder and crank the engine.
  3. Record the compression reading and repeat for all cylinders; compare results to manufacturer specifications (typically around 180-200 psi).
  4. If any cylinder has low compression, further investigation into internal engine issues (e.g., valve problems, piston rings) may be necessary.