A8L Quattro Sedan V8-4.2L (BVJ) (2007)
Fuel Pressure Release: Service Precautions
High Side Fuel Pressure, Reducing
CAUTION!
The fuel injection system is separated into a high pressure side (maximum approximately 150 bar) and a low pressure side (approximately
7 bar).
Before opening the high pressure side, for example, removing the high pressure pump, fuel rail, fuel injectors, fuel pipes or fuel pressure
sensor, the fuel pressure must be reduced to a residual pressure of approximately 7 bar. The procedure for this is as follows.
Special tools, testers and auxiliary items required
‹› Vehicle diagnostic, testing, and information system (VAS 5051B)
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Connect the (VAS 5051B).
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Start the engine and run at idle speed.
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Select the "engine electronics" in On Board Diagnostics (OBD).
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Then select "Measured values" read out.
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Select measured value block 140.
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With the engine running in idle, the fuel pressure will be displayed in display field 3.
‹› Specified value: between 35 and 45 bar
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With the engine in idle, remove the fuse - in the relay/fuse carrier in the luggage compartment on the right side - for the fuel pump control
module.