With Generic Scan Tool

Fuel Pressure Regulator And Residual Pressure, Checking

The fuel pressure regulator controls the fuel pressure as a function of the Manifold Absolute Pressure (MAP).

The specified value for this test is dependent on the working pressure of the Fuel Pump (FP). This is about 4.0 bar positive pressure

Special tools and equipment







- VAG1318 pressure gauge







- VAG1318/6+7 adapter







- VAG1318/17 (2x)

WARNING: Fuel system is under pressure. Before opening system, place rags around the connection point. Then release pressure by carefully loosening connection.

Test sequence







- Remove engine cover (arrows).







- Remove bolt -1- and remove reservoir cover (arrow).
- Open fuel filler flap briefly (pressure release).







- Disconnect fuel supply line -1- by pressing release button.







- Connect VAG1318 using adapters 1318/7 and 1318/17 (2 pieces) at supply line.
- Open shut-off valve of pressure gauge. The lever points in the direction of flow.
- Start engine and let run at idle.
- Measure fuel pressure.
Specified value: about 2.5 bar positive pressure







- Disconnect vacuum hose at fuel pressure regulator.
- Fuel pressure must rise to about 3.0 bar positive pressure.
- Switch ignition off.
- Check for proper seal and residual pressure by observing pressure drop on pressure gauge.
- After 10 minutes, there must be at least 1.5 bar positive pressure

If residual pressure sinks below 1.5 bar positive pressure:
- Start engine and let run at idle.







- Wait until pressure has risen, and then switch off ignition. Simultaneously close shut-off valve of VAG1318 pressure gauge (lever perpendicular to direction of flow -arrow-).
- Observe pressure drop on pressure gauge.

If pressure does not drop now:
- Test check-valve on Fuel Pump (FP).

If pressure drops again:
- Open shut-off valve of VAG1318 pressure gauge (lever in direction of flow).
- Start engine and let run at idle.
- Wait until pressure has risen, and then switch off ignition. Simultaneously clamp return line (with blue marking) completely closed.

If pressure does not drop now:
- Replace fuel pressure regulator

If pressure drops again:
- Check line connections, O-rings at fuel distributor and fuel injectors for proper seal.
- Check whether pressure gauge is properly sealed.

NOTE: Before disconnecting pressure gauge, release fuel pressure by opening shut-off valve. Hold a container in front of connection for this.