Pressure Retention Valve In Fuel Return Line, Checking

Pressure Retention Valve in Fuel Return Line, Checking

The pressure retention valve in the fuel return maintains a residual pressure of approximately 10 bar.

The fuel injectors require this control quantity to function correctly.

Special tools, testers and auxiliary items required

• Tester for Fuel Return System (VAS 6330)


• Follow the guidelines for a clean working environment when working on the fuel system. Refer to => [ Fuel System ] Fuel System.

• Always follow these rules before and during work.

- Remove engine cover. Refer to => [ Engine Cover ] Service and Repair.

- Remove the noise insulation from the injectors.

- Before removing, clean the cylinder 1 return line connection using a commercially available detergent, for example.

- Dry the return line connection on cylinder 1.

- Cover the cylinder 1 return line connection with a cloth.

- Push both brackets down and at the same time pull the release bolts upwards - arrow - and remove the return line connections on cylinder 1.






• Maintain clean working conditions. Dirt and contaminants must not enter the return line and the connection on the fuel injectors.

- Install the (VAS 6330) between the fuel injector return line connection and the return line.






- Start the engine.

- Check the pressure on the tester.

• Specified value: approximately 10 bar

If the specified value is not reached, replace the check valve.

• The check valve can be replaced only with the complete fuel return lines.