Checking intake manifold pressure sender — AUDI

Note:

Only gold-plated contacts may be used when servicing the sender connector contacts

Special tools, workshop equipment, testers, measuring instruments and auxiliary items required

Fault reader V.A.G 1551 or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3A
Test box V.A.G 1598/31
Hand multimeter V.A.G 1526 or multimeter V.A.G 1715
Adapter set V.A.G 1594
Current flow diagram

Test sequence

Connect fault reader V.A.G 1551 (V.A.G 1552). Start engine and select "Address word" 01 of engine control unit. When doing this the engine must be running at idling speed.
(Connecting fault reader and selecting engine control unit
=> Page
01-13
.)

Rapid data transfer
HELP
Select function XX
Indicated on display:

Press keys 0 and 8 for the function "Read measured value block" and confirm entry with Q key.

Read measured value block
HELP
Input display group number XXX
Indicated on display:

Press keys 0, 0 and 3 for "Display group number 3" and confirm entry with Q key.

Read measured value block 3
⇒
1
2
3
4
Indicated on display:
(1...4 = Display zones)

Read off the displayed value for intake manifold pressure in display zone 2 and note this value.
Briefly open throttle valve. The intake manifold pressure value must increase briefly.

If the display shows constantly 91 mbar or 1254 mbar:

Display · Cause · Continuation of check
91 mbar · Open circuit or short to earth · => Page 24-54
1254 mbar · Short to positive · => Page 24-56

Continuation of check when display shows 91 mbar:

Pull 4 pin connector off intake manifold pressure sender (G71) with intake air temperature sender (G42) -arrow- (engine can stall).

Bridge connector contacts 3+4 with aux. cables from V.A.G 1594 and observe display.

If the display jumps to 1254 mbar:

Press ⇒key.
Press keys 0 and 6 for the function "End output" and confirm entry with the Q key.
Switch off ignition.

Renew the intake manifold pressure sender (G71) with intake air temperature sender (G42)
=> Page
24-21
, item
11
.

If the display remains at 91 mbar:

Press ⇒key.
Press keys 0 and 6 for the function "End output" and confirm entry with the Q key.
Switch off ignition.
Connect test box V.A.G 1598/31 to control unit wiring harness. The engine control unit remains disconnected => Page
24-8
.

Check wiring for open circuit between test box and connector using current flow diagram.
Contact 3+socket 98
Contact 4+socket 109
Wire resistance: Max. 1.5 ω
Additionally check wiring contact 4 for short to earth and to contact 1.
Specification: ∞ω

If no fault is detected in the wiring:

Renew engine control unit => Page
24-126
.

Continuation of check when display shows 1254 mbar:

Pull 4 pin connector off intake manifold pressure sender (G71) with intake air temperature sender (G42) -arrow- (engine can stall).

If the display jumps to 91 mbar:

Press ⇒key.
Press keys 0 and 6 for the function "End output" and confirm entry with the Q key.
Switch off ignition.
Renew the intake manifold pressure sender (G71) with intake air temperature sender (G42)
=> Page
24-21
, item
11
.

If the display remains at 1254:

Press the ⇒key.
Press keys 0 and 6 for the function "End output" and confirm entry with the Q key.
Switch off ignition.

Release connector from control unit and pull off.

Check wiring to control unit connector at 4 pin connector contact 4 for short to wire contact 3 and to battery positive.
Specification: ∞ω

If no fault is detected in the wiring:

Renew engine control unit => Page
24-126
.