Checking altitude sender -F96: Audi 2.2 (AAN)

Special tools and workshop equipment required

V.A.G 1397 A
V.A.G 1526 A
V.A.G 1594 A
V.A.G 1598 A with V.A.G 1598/5
VAS 5051 with VAS 5051/1 and VAS 5051/2

Check function

Read measured value block, display group 002, ignition switched on => Page
01-69
.

Display on VAS 5051:

Check display in display zone -4-.
Specification: current air pressure in mbar

Switch on turbocharger tester V.A.G 1397 A and set measuring range selector switch to position -I- (absolute pressure).
The display must approximately correspond to that on the display of VAS 5051

Notes:

The current air pressure is dependent on the altitude and the pressure conditions affected by the weather.
The air pressure at sea level is approx. 1013 mbar in normal weather conditions. It decreases approx. 100 mbar for every 1000 m above sea level.
The pressure fluctuations caused by the weather are usually less than ±50 mbar (except for extreme weather situations and tropical countries).
When the altitude sender fails, the control unit uses a substitute value of 968 mbar (corresponds to 3000 m above sea level).

If the display in display zone 4 is unrealistic or if 968 is constantly displayed:

Check power supply

Remove the lower part of the right A pillar trim and the front door sill panel tread strip

=> General Body Assembly; Repair group 70; Trims
General Body Assembly
Trims

Pull back floor covering at front of right footwell (if necessary, cut open the perforated seam on the left with a knife).

Unscrew bolts -arrows- for electronics box cover.
Carefully detach upper and lower sections of cover.

Unplug electrical connector -arrow- from altitude sender.

Connect multimeter as follows to measure voltage.

Connector / Contact · Measure to
2 · Engine earth

Switch the ignition on.
Specification: approx. 5 V

If specification is not attained:

With the ignition switched off, use adapter V.A.G 1598/5 to connect test box V.A.G 1598 A to connector of engine control unit (control unit remains disconnected) => Page
24-15
.
Check for open circuit and short to positive or earth in the following wiring connections:

Connector / Contact · Test box V.A.G 1598 A / Socket
2 · 12

Use current flow diagram to eliminate open circuit in wiring/short circuit.

If no wiring fault is detected:

Replace engine control unit => Page
24-18
.

If specification is attained:

Switch the ignition on.
Connect multimeter as follows to measure voltage.

Connector / Contact · Specified value
1 + 3 · 4.5...5.0 V
2 + 3 · 4.5...5.0 V

If the specifications are not obtained:

Eliminate open circuit using the current flow diagram.

If specifications are attained:

With the ignition switched off, use adapter V.A.G 1598/5 to connect test box V.A.G 1598 A to connector of engine control unit (control unit remains disconnected) => Page
24-15
.
Check for open circuit and short to positive or earth in the following wiring connections:

Connector / Contact · Test box V.A.G 1598 A / Socket
1 · 9
3 · 30

Use current flow diagram to eliminate open circuit in wiring/short circuit.

If no wiring fault is detected:

Replace altitude sender.