why does my Toyota Corolla E170 (2013-2019) check engine light keep coming back

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, vacuum gauge, fuel pressure gauge.
• Gather necessary safety equipment, including gloves and safety glasses.

2. Address Diagnostic Trouble Codes

• If codes indicate a specific issue (e.g., P0420 for catalytic converter efficiency), proceed to inspect and replace the affected component.
  • Sub-steps:
    • Research specific DTCs to understand the underlying problem.
    • For codes related to the catalytic converter, check for physical damage or blockage.
    • If necessary, replace the catalytic converter. Use OEM parts for best results.

3. Inspect and Replace Spark Plugs and Ignition Coils

• Tools Required: Socket set, torque wrench.
• Sub-steps:
  • Remove the engine cover if applicable.
  • Disconnect the ignition coil connectors and remove the coils.
  • Remove the spark plugs using a spark plug socket.
  • Inspect plugs for wear and carbon buildup. Replace if necessary.
  • Install new spark plugs, torquing them to manufacturer specifications (usually around 13-15 lb-ft).
  • Reinstall ignition coils and reconnect the connectors.

4. Check and Repair Vacuum Leaks

• Tools Required: Vacuum gauge, hose clamps.
• Sub-steps:
  • Use a vacuum gauge to check for proper vacuum readings.
  • Inspect all vacuum hoses for cracks or disconnections.
  • Replace any damaged hoses and ensure all connections are secure.

5. Test and Repair Fuel System

• Tools Required: Fuel pressure gauge.
• Sub-steps:
  • Connect the fuel pressure gauge to the fuel rail.
  • Turn the ignition to the "ON" position without starting the engine to check for initial fuel pressure.
  • If pressure is low, inspect the fuel pump and fuel filter.
  • Replace any faulty components to restore proper fuel pressure.