With Manufacturer's Scan Tool

Fuel pressure regulator and holding pressure, checking

Engines: AVH, AZG

The fuel pressure regulator regulates the fuel pressure depending on intake manifold pressure.

Special tools and equipment





- VAG 1318 Pressure gauge
- 1318/10 Adapter
- 1318/11 Adapter
- 1318/16 Hose adapter
- VAG 1921 Spring-type clip pliers

Work sequence




- Remove fuse No. 28 (fuel pump) from fuse holder.

WARNING: The fuel system is under pressure! Before opening the system place a cloth around the connection. Then release the pressure by carefully loosening the connection.






- Remove supply line -1- and collect leaking fuel with a cloth.






- Connect pressure tester VAG 1318 with adapters VAG 1318/10, VAG 1318/11 and VAG 1318/6.
- Open pressure tester shut-off valve. The handle points in through-flow direction (arrow).
- Install fuse 28 (fuel pump) in fuse holder
- Start engine and run at idling speed.
- Measure fuel pressure.
- Specification: approximately 2.5 bar






- Disconnect vacuum line -1- from union -2-. The fuel pressure must increase to: approximately 3.0 bar

If specification is not obtained:
- Check quantity supplied by fuel pump

If specification is obtained:
- Switch ignition off.

- Hold pressure and check for leaks. Observe pressure drop on gauge. After 10 minutes, there must be a residual pressure of at least 2.0 bar.

If holding pressure drops below 2 bar:
- Start engine and run at idling speed.






- Switch ignition off after the pressure has build-up. At the same time close pressure tester VAG 1318 shut-off tap (handle at right angles to through-flow direction -arrow-).
- Observe pressure drop on gauge.

If pressure does not drop
- Check fuel pump non-return valve

If pressure drops again:






- Open shut-off tap on pressure tester VAG 1318 (handle point in direction of flow -arrow-).
- Start engine and run at idling speed.






- Switch ignition off once the pressure has built-up and clamp off return hose at same time.
- If pressure does not drop:
- Replace fuel pressure regulator
- Erase DTC memory to return learned values to a neutral (default) position.
Reading Diagnostic Trouble Codes
Clearing Diagnostic Trouble Codes

If pressure drops again:
- Check line connections, O-rings on fuel rail and injectors for leaks.
- Checking pressure tester for leaks.

If a leak on vehicle has been rectified.
- Erase DTC memory to return learned values to a neutral (default) position.
Reading Diagnostic Trouble Codes
Clearing Diagnostic Trouble Codes

Note: Before removing the pressure tester, remove fuse 28 again and place a cloth around the connection to be loosened.