Procedure that must be performed before opening the high-pressure fuel injection system - Pay close attention!

• The fuel injection system is separated into a high-pressure section (max. approx. 120 bar) and a low-pressure section (approx. 6 bar).
• Before opening the high pressure section (e.g. to remove high pressure pump, fuel rail, fuel injectors or any other component or fuel line located in high pressure area of fuel injection system), fuel pressure in high pressure area must be dissipated in a defined manner to a residual pressure of approx. 6 bar. The procedure for this is as follows.

Special tools, testers and auxiliary items required 

Fig 1: Identifying Vehicle Diagnosis, Testing And Information System VAS 5051B

Courtesy of VOLKSWAGEN UNITED STATES, INC.

• Vehicle diagnostic, testing, and information system VAS 5051B (VAS 5051 B version shown as example only)

Work procedure 

• Start engine and run at idle speed.

Fig 2: Connecting Vehicle Diagnosis, Testing Info. System VAS 5051B

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• Connect Vehicle Diagnosis, testing info. system VAS 5051B.

Fig 3: Display On VAS 5051 - "On Board Diagnostic (OBD)"

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Display on VAS 5051B :

• In selection - 1  - , press "On Board Diagnostic (OBD)" system and activate by pressing → button.

Fig 4: Display On VAS 5051 - "01 - Engine Electronics"

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Display on VAS 5051B :

• In selection - 1  - , press "01 - Engine electronics" vehicle system and activate by pressing → button.

Fig 5: Display On VAS 5051 - "006 - Basic Setting"

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Display on VAS 5051B :

• In selection - 1  - , press "011 - Measured values" and activate by pressing → button.

Fig 6: Display On VAS 5051 - "Display Group 140"

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Display on VAS 5051B :

• In button field - 1  - , press 1 4 0 buttons for "Display group 140" and confirm entry by pressing Q button.

Fig 7: Display On VAS 5051 - (Read-Out For Fuel Pressure In Fuel Rail)

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Display on VAS 5051B :

• Check read-out for fuel pressure in fuel rail in display field - 3  -.

Example:

3 - 40.63 bar

Fig 8: Disconnecting Electrical Connector At Fuel Metering Valve 2 N402 On Left High Pressure Pump

Courtesy of VOLKSWAGEN UNITED STATES, INC.

• Disconnect electrical connector - arrow  - at Fuel Metering Valve 2 N402 on left high pressure pump.

Fig 9: Disconnecting Electrical Connector At Fuel Metering Valve 2 N290 On Right High Pressure Pump

Courtesy of VOLKSWAGEN UNITED STATES, INC.

• Disconnect electrical connector - arrow  - at Fuel Metering Valve 2 N290 on right high pressure pump.

Fig 10: Display On VAS 5051 - (Read-Out For Fuel Pressure In Fuel Rail)

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Display on VAS 5051B :

• Check read-out in display field - 3  - :

• Fuel pressure in fuel rail must sink to approx. 6 bar.

• Switch off ignition.

The fuel rail will continue to be filled with fuel, but it will no longer be under high pressure.

Now components or lines can be opened. Lay a clean cloth around connection points and collect escaping fuel.

Final procedures 

• Reconnect electrical harness connectors.
• In "Guided Functions" operating mode, generate readiness code for engine control module (ECM).