how to diagnose P0303 code on my Volkswagen Golf MK7 (2015-2019)

Solution

1. Preparation

• Gather tools and required parts.
• Disconnect the battery to prevent electrical shorts.
• Allow the engine to cool down before starting work.

2. Inspect and Replace Ignition Components

• Tools Required: Socket set, torque wrench, ignition coil puller.
• Remove the engine cover (if applicable) and locate the ignition coils for cylinder 3.
• Unplug the electrical connector from the ignition coil.
• Remove the ignition coil using the appropriate socket size.
• Inspect the spark plug for wear; replace if necessary.
• Install a new spark plug (use OEM specifications for gap).
• Reinstall the ignition coil and torque it to the manufacturer’s specifications (usually around 10-15 Nm).
• Reconnect the electrical connector.

3. Check and Replace Fuel Injector

• Tools Required: Fuel injector puller (if necessary), clean rag, fuel line clamps.
• Ensure the fuel system is depressurized by removing the fuel pump fuse and starting the engine until it stalls.
• Disconnect the electrical connector from the fuel injector.
• Remove the fuel rail (if necessary) to access the injector for cylinder 3.
• Replace the fuel injector with a new one, ensuring proper seating and using new O-rings.
• Reassemble the fuel rail and reconnect all necessary components.

4. Perform Compression Test

• Tools Required: Compression tester.
• Remove the spark plug from cylinder 3.
• Screw the compression tester into the spark plug hole.
• Crank the engine several times and note the compression reading.
• Compare it to the manufacturer’s specifications (should typically be around 190-210 psi).
• If low, further investigation may be required for potential mechanical issues.