why does my Volkswagen Golf MK5 (2004-2008) check engine light stay on after resetting

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the battery to prevent electrical shorts.

2. Address Error Codes

• Sub-step 1: Using the OBD-II scanner, document all error codes and research their meanings.
• Sub-step 2: Clear the error codes and monitor for any immediate reappearance after a short drive.

3. Inspect and Replace Components

• Sub-step 1: If codes indicate a faulty MAF sensor, remove it using a Torx screwdriver and replace it with a new one.
• Sub-step 2: If spark plugs or ignition coils are faulty, remove engine cover, disconnect wiring harness, and replace them as needed. Ensure proper torque (usually around 20 Nm) when reinstalling.
• Sub-step 3: For vacuum leaks, inspect all hoses and replace any cracked or damaged hoses.

4. Fuel System Check

• Sub-step 1: Attach a fuel pressure gauge to the fuel rail and check for proper fuel pressure as specified in the service manual.
• Sub-step 2: Replace the fuel filter if pressure is low or if the filter has not been changed per maintenance schedule.

5. Final Assembly

• Reconnect the battery and ensure all components are correctly installed.
• Start the engine and allow it to reach normal operating temperature.