audi Workshop Repair Guides

Audi Workshop Service and Repair Manuals

Engine control unit > < Lambda probes
Safety precautions and instructions for working on the fuel system
Safety precautions and instructions for working on the fuel system
  WARNING
The fuel system operates at extremely high pressure. This can cause injury.
t  If the battery is not disconnected, the fuse for the fuel pump control unit -J538- must be removed as a precautionary measure before opening the fuel system because the fuel pump will otherwise be activated by the contact switch on the driver's door.
t  The fuel system is pressurised. The fuel pressure in the high-pressure section of the injection system must be reduced to a residual pressure prior to opening; for procedure see → Chapter.
t  The connection must be opened immediately after reducing the pressure; wrap a cloth around the connection and allow the residual pressure (approx. 7 bar) to dissipate.
  Note
Removing the fuse (located in fuse carrier in dash panel on driver's side) will interrupt the power supply from »terminal 30« for the fuel pump control unit -J538-. → Current flow diagrams, Electrical fault finding and Fitting locations
Even small amounts of dirt can cause malfunctions. For this reason, please observe the following rules when working on the fuel supply system and injection system:
t  Carefully clean connection points and the surrounding area with engine cleaner or brake cleaner and dry thoroughly before opening.
t  Plug open lines and connections with suitable protective caps immediately.
t  Place parts that have been removed on a clean surface and cover them over. Do not use fluffy cloths.
t  Only install clean components; replacement parts should only be unpacked immediately prior to installation. Do not use parts that have been previously unpacked and stored away loose (e.g. in toolboxes, etc.).
t  When the system is open: Do not work with compressed air. Do not move the vehicle unless absolutely necessary.
   

Engine control unit > < Lambda probes