Testing Hall sensor: Audi (AEB, AHK)

Hall sensor -G40 is located at the rear of the left-hand cylinder head => for fitting location refer to Page
24-5
.

Note:

In normal operation, the engine control unit detects the ignition position for cylinder 1 from the Hall sensor signal and performs ignition for each cylinder during every second engine revolution.
The engine starts and even runs if the Hall sensor is faulty or if the connector is unplugged, as the engine control unit performs an ignition on each cylinder for every revolution of the engine when a fault is detected.
The fact that the control unit is out of phase by one engine revolution does not have any noticeable effect on the injection system. If this happens, the fuel is injected "upstream" (before the closed inlet valve) instead of while the inlet valve is open. This has only a minor influence on the quality of the air/fuel mixture.

Push back rubber grommet at connector of Hall sensor (connector remains connected to Hall sensor).

Connect diode test lamp V.A.G 1527 from the rear to contacts 1 and 2.

Note:

Connector contacts are numbered accordingly on the back of the connector.

Operate starter for a few seconds.

The diode test lamp must flash briefly on every second engine revolution.

Pull connector off Hall sensor.
Switch ignition on.
Connect handheld multimeter V.A.G 1526 to contacts 1 and 3 of the Hall sensor connector.

Specification: 4.5 ... 5.5 V

Connect handheld multimeter V.A.G 1526 to contacts 2 and 3 of the Hall sensor connector.

Specification: Battery voltage

If the specified values are attained and the diode test lamp does not flash, replace the Hall sensor.

If the specified values are not attained, check the wiring as follows:

Connect test box V.A.G 1598/19 to wiring harness for engine control unit =>Page
24-14
.
Check the wiring connection from the Hall sensor ...

... to engine control unit for open circuit and short to positive or earth.

Contact on connector for Hall sensor · Test box V.A.G 1598/19 or engine control unit
1 / 2 / 3 · A3 (positive, 5 V) / B2 (signal) / D11 (earth)

First of all, erase the fault memory as a check. If a fault relating to the camshaft sensor (Hall sensor) is displayed again although the previous tests were OK, unbolt the Hall sensor and check whether the rotor orifice at the camshaft is correctly installed. (If not correctly installed, the detent lug is damaged when the securing bolt is tightened.)
If the position of the rotor orifice is OK, check the setting of the toothed belt of the camshaft / crankshaft.

=> 8-cylinder engine, Mechanical components; Repair Group 15; Removing and installing toothed belt
8-cylinder engine, Mechanical components
Removing and installing toothed belt