Checking intake manifold pressure sender G71 and altitude sender F96 — VW

Checking
intake manifold pressure sender
G71
and
altitude sender
F96
Engine codes AGR, AHF, ALH, ASV
Special tools and workshop equipment required
Fault reader
V.A.G 1551
or
vehicle system tester
V.A.G 1552
with
diagnosis cable
V.A.G 1551/3
Adapter cable, 121-pin
V.A.G 1598/31
Hand multimeter
V.A.G 1526C
or
multimeter
V.A.G 1715
Turbocharger tester
V.A.G 1397A
Auxiliary measuring set
V.A.G 1594C
Current flow diagram
Altitude sender
F96
is located in
diesel direct injection system control unit
J248
. The
intake manifold pressure sender
G71
is a separate component and is located together with
intake manifold temperature sender
G72
in a common housing on the charge air cooler.
Test procedure
Connect
fault reader
V.A.G 1551
or
vehicle system tester
V.A.G 1552
and select engine electronics control unit with
“address word 01”
. The ignition must be switched on for this purpose. (Connecting fault reader and selecting engine electronics control unit
Chapter
.)
Indicated on display:
Rapid data transfer HELP
Select function XX
Press buttons
0
and
8
for function
“Read measured value block”
and confirm entry with
Q
button.
Indicated on display:
Read measured value block HELP
Input display group number XXX
Press buttons
0
,
1
and
0
for
“Display group number 10”
and confirm entry with
Q
button.
Compare display in display zone 2 (
altitude sender
F96
), display zone 3 (
intake manifold pressure sender
G71
) and display on
turbocharger tester
V.A.G 1397A
with one another. Specification:
Read measured value block 10 ->
0 mg/H 1027 mbar 1013 mbar 0.0%
Pressures must correspond (tolerance ± 30 mbar)
Note
The
turbocharger tester
V.A.G 1397A
is required to provide an independent figure for comparison. The
turbocharger tester
V.A.G 1397A
must be set to measuring range I (absolute pressure). A barometer can be used instead.
Value in display zone 2 deviates:
Press
→
button.
Press buttons
0
and
6
for function
“End data transfer”
and confirm entry with
Q
button.
Switch off ignition.
Renew
diesel direct injection system control unit
J248
Chapter
.
Value in display zone 3 deviates:
Remove right headlight
Electrical system
Rep. Gr.
94
Removing and installing headlight
Press
→
button.
Press buttons
0
and
6
for function
“End data transfer”
and confirm entry with
Q
button.
Start engine and select function 08
“Read measured value block”
again.
Press buttons
0
,
1
and
0
for
“Display group number 10”
and confirm entry with
Q
button.
Disconnect connector for
intake manifold pressure sender
G71
Chapter
.
Observe value in display zone 3 (
intake manifold pressure sender
G71
).
It must drop briefly to approx. 400 mbar and then assume the value of the
altitude sender
F96
(display zone 2).
Read measured value block 10 ->
515 mg/H 1009mbar 1009 mbar 0.0%
If the specification is attained:
Renew
intake manifold pressure sender
G71
with
intake manifold temperature sender
G72
.
If the specification is not achieved:
Press
→
button.
Press buttons
0
and
6
for function
“End data transfer”
and confirm entry with
Q
button.
Switch off ignition.
Connect
adapter cable, 121-pin
V.A.G 1598/31
to control unit wiring harness.
Check wiring between
adapter cable, 121-pin
V.A.G 1598/31
and connector for open circuit referring to current flow diagram.
Contact 3+socket 31 Contact 4+socket 71 Line resistance: Max. 1.5 Ω
Also check wiring for short to one another, short to vehicle earth and short to battery positive.
Specification: ∞ Ω.
If no fault in lines is detected:
Renew
diesel direct injection system control unit
J248
Chapter
.