Audi Workshop Service and Repair Manuals

Checking fuel pressure sender -G247- Special tools and workshop equipment required

t  Pressure sensor tester -VAS 6394- t  Socket, 27 mm, long (commercially available) t  Test instrument adapter -VAS 5570- Procedure   WARNING The injection system consists of a high-pressure section (maximum approx. 120 bar) and a low-pressure section (approx. 6 bar). Prior to opening the high-pressure section, the fuel pressure in the high-pressure section must be reduced in a controlled manner to a residual pressure of approx. 6 bar. The procedure is described in → Chapter, Reducing fuel pressure in high-pressure section of fuel system. –  Unplug connector -1- and remove fuel pressure sender -G247--2-.

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–  Lubricate taper seal of adapter -VAS 6394/3- with clean engine oil and screw into fuel rail. Tightening torque: 22 Nm.

–  Unscrew plug -2- and screw fuel pressure sender -G247- into tester -VAS 6394/1-. Tightening torque: 22 Nm. –  Connect pressure line of tester -VAS 6394/1- to adapter -VAS 6394/3-.

–  Use test instrument adapter -VAS 5570- to make electrical connection between vehicle and fuel pressure sender -G247-.

–  Switch on tester -VAS 6394/1- by pressing button -A- once briefly.   Note t  You can press and hold button -A- for 2 seconds to switch on the illumination for 20 seconds. t  If tester -VAS 6394/1- does not indicate 0 bar, zero the tester → Operating instructions. –  Connect up the vehicle diagnostic, testing and information system -VAS 5051B-. –  Start engine and run at idling speed. –  Select „Engine electronics“ in vehicle self-diagnosis. –  Then select function read „Measured values“. –  Select „Fuel pressure“ from the list. –  Compare fuel pressure indicated on tester -VAS 6394/1- with the value displayed on the vehicle diagnostic tester. l  The pressure readings must not deviate by more than 5 bar. –  If the deviation is more than 5 bar, renew fuel pressure sender -G247-.   WARNING The fuel system is pressurised. The fuel pressure in the high-pressure part of the injection system must be reduced to a residual pressure prior to opening; for procedure see → Chapter. –  Screw a new fuel pressure sender -G247- into the pressure gauge -VAS 6394/1-. –  Repeat the test with the new fuel pressure sender -G247- and compare the two pressure values. If the values agree: –  Install the new fuel pressure sender -G247- → Chapter. If the two values still do not agree: –  Check the electrical connection between the fuel pressure sender -G247- and the engine control unit; refer to → Current flow diagrams, Electrical fault finding and Fitting locations.