Audi Workshop Service and Repair Manuals

The needle lift sensor signal is used to determine the commencement of injection. If it fails, injection start switches to open loop control (according to engine speed and engine load). During normal operation, injection start is controlled by a closed loop function (according to engine speed, engine load and temperature).

Checking engine speed sensor electrically

• ‒ Switch ignition off.
• ‒ Detach the connector for the sensor=> overview of fitting locations, Page 23-4.

• ‒ → Connect the hand-held multimeter for resistance measurement between the contacts on the sensor connector.

• Specified value: 90 ... 120 ω (with a hot engine the resistance may be up to 20 ω higher)

If specified value is not attained:

• ‒ Replace the injector cyl. 3 with needle lift sensor (G80)

If specified value is attained:

Checking wiring

• ‒ Connect test box V.A.G 1598/22 to wiring harness for engine control unit =>Page 23-46.

The following wiring connections are to be checked for open circuits and/or short to positive or negative.

• ‒ Rectify any open/short circuit as necessary.

=> Current Flow Diagrams, Electrical Fault-finding and Fitting Locations binder