Volkswagen Workshop Service and Repair Manuals > Golf Mk6 > Power unit | 4-cylinder diesel engine (1.6 l engine, common rail) | Fuel preparation system Diesel injection | Injectors, high pressure accumulator | Checking pressure retention valve in fuel return line.

Checking pressure retention valve in fuel return line.

The pressure retention valve maintains a residual pressure of approx. 1 bar in the return lines.

This residual pressure is required for the control function of the injectors.

Special tools and workshop equipment required

t	Pressure gauge -VAS 6330-

t	Adapter -VAS 6330/3-1-

t	Adapter -VAS 6330/3-2-

–	Remove engine cover panel → Chapter.

–	Clean return line connection on cylinder 1 (e.g. with cold cleaner) before removing.

–	Dry return line connection on No. 1 cylinder.

–	Cover return line connection on No. 1 cylinder with a cleaning cloth.

–	Pull return line connection off No. 1 cylinder; pull out release clip to do this.

Note

t	Open the return line connection with a narrow screwdriver and long-nosed pliers.

t	Adhere strictly to rules of cleanliness. No dirt must be allowed to enter the disconnected fuel return lines or the open connections on the injectors.

t	Always renew clips.

–	Install tester for fuel return system -6330- with adapters -VAS 6330/3-1- and -VAS 6330/3-2- between return line connection on injector and return line.

–	Start engine.

–	Check pressure on pressure gauge.

t	Specification: approx. 1.0 bar

If the value does not match the specification, fit a new pressure retention valve.

After any work on the fuel system

l	Observe instructions for working on fuel system → Chapter.

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