With Generic Scan Tool

System Pressure And Residual Pressure, Checking

NOTE: Fuel pressure regulator is integrated in fuel filter (under fuel tank) and cannot be replaced individually.

Recommended special tools and equipment

- Fuel Inj. Pressure Gauge Set V.A.G 1318 with adapters V.A.G 1318/6 and V.A.G 1318/7

Test requirements:
- Fuel Pump (FP) Relay OK; checking. Testing and Inspection
- Delivery quantity of Fuel Pump (FP) OK; check. Testing and Inspection
- Fuel filter OK
- Parking brake engaged.
- Vehicles with automatic transmission: Selector lever in position "P" or "N".
- Electrical consumers switched off (radiator fan must NOT run during test).
- A/C switched off.
- Ignition switched off.

Checking system pressure

- Remove engine cover (arrows).
- Open fuel filler flap briefly (pressure release).

CAUTION:
- Work on the fuel system must only be performed when engine is cold.
- Fuel system is under pressure. Before opening system, place rags around the connection point. Then release pressure by carefully loosening connection.

- Open threaded connection -1- and catch escaping fuel using a rag.
- Connect V.A.G 1318 pressure gauge in supply line using adapters 1318/6 and 1318/7.

- 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: approx. 4.0 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 2.5 bar positive pressure

If residual pressure sinks below 2.5 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 V.A.G1318 pressure gauge (lever perpendicular to direction of flow -arrow-).
- Observe pressure drop on pressure gauge.

If pressure drops again:
- Check pressure gauge for proper seal.
- Check line connections and fuel injectors for proper seal.

If pressure does not drop now:
- Check pressure regulator in fuel filter:
- Vehicles with Front Wheel Drive (FWD)
- Vehicles with All Wheel Drive (AWD)

Checking fuel pressure regulator - Vehicles with Front Wheel Drive (FWD):

Sedan:
- Remove luggage compartment lining.
- Push forward the right backrest of rear seat, if necessary.

Avant:
- Remove left 1/3 backrest.
- Remove left side trim in luggage compartment and dirt tray.

All:

- Remove cover for connector flange (arrows).

- Disconnect fuel return line -2- (press release button).

- Connect V.A.G 1318/17-1 adapter piece to return line.
- Pinch off adapter piece using 3094 hose clamps.

NOTE: 3094 hose clamps must not be placed directly on fuel line, otherwise it may be damaged.

- Start engine and let run at idle.

- Wait until pressure has risen, and then switch off ignition. Simultaneously close shut-off valve of V.A.G1318 pressure gauge (lever perpendicular to direction of flow -arrow-).
- Observe pressure drop on pressure gauge.

If pressure drops again, check-valve of fuel pump is leaky.
- Replace fuel pump.

If pressure does not drop now:
- Replace fuel filter with integrated fuel pressure regulator.

Assembly is performed in the reverse order of removal, noting the following:

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

Checking fuel pressure regulator - Vehicles with All Wheel Drive (AWD):
- Remove rear seat bench.

- Remove cover for left connector flange (arrows).

- Disconnect fuel return line (arrow) from connector flange (left side of vehicle).

- Wait until pressure has risen, and then switch off ignition. Simultaneously close shut-off valve of V.A.G1318 pressure gauge (lever perpendicular to direction of flow -arrow-).
- Observe pressure drop on pressure gauge.

If pressure drops again, check-valve of fuel pump is leaky.
- Replace fuel pump.

If pressure does not drop now:
- Replace fuel filter with integrated fuel pressure regulator.

Assembly is performed in the reverse order of removal, noting the following:

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

Final procedures
After repair work, the following work steps must be performed in the mentioned sequence:
1. Check DTC memory.
2. necessary, erase DTC memory see "Mode 4: Reset/erase diagnostic data".
3. Generate readiness code. Readiness Code, Generating

- End diagnosis and switch ignition off.