1996 AUDI A4 OBD port

01-49

Output on GST
and/or on VAG 1551
scan tool Possible malfunction cause

Malfunction repair
P0156 / 16540
O2 Sensor Circuit
Malfunction (Bank 2
Sensor 2) Harness connector for Oxygen Sensor (O2S) 2
behind Three Way Catalytic Converter (TWC) -
G131- (B2-S2) loose or corroded due to moisture
in the harness connector

- Check harness connector for tight fit
and contact corrosion, if necessary
reconnect and/or clean, installation
location page 24
-1

Malfunction cause found: Yes
No

- Erase DTC memory, test drive and
check DTC memory again
MIL Status:
MIL lights up
immediately
Wiring connection to Oxygen Sensor (O2S) 2
behind Three Way Catalytic Converter (TWC) -
G131- (B2-S2) faulty, or sensor -G131- faulty

- Check O2S 2 behind three way
catalytic converter -G131- (B2-S2)
page 24
-53


Malfunction cause found: Yes
No

- Erase DTC memory, test drive and
check DTC memory again
For troubleshooting
Display group 041
Engine Control Module (ECM) -J192- faulty

- Replace and code engine control
module page 01
-265
erase DTC
memory and test drive check DTC
memory
Notes:
The malfunction "P0156 / 16540" is set 123 sec after engine start, at a coolant temperature over 80 C (176 F) and 45 sec
Pa
ge 65 of 366 On Board Dia
gnostic
(OBD
) - Multi
port Fuel In
jection
(MFI
)
11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU01.01.1

after the probe heater behind the Three Way Catalytic Converter (TWC) is switched on , as soon as the signal voltage during
a deceleration fuel shut off is greater than 300 mV. The length of the deceleration fuel shut off must be longer than 4 sec.
Pa
ge 66 of 366 On Board Dia
gnostic
(OBD
) - Multi
port Fuel In
jection
(MFI
)
11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU01.01.1

01-50

Output on GST and/or
on VAG 1551 scan
tool Possible malfunction cause

Malfunction repair
P0158 / 16542
O2 Sensor Circuit High
Voltage (Bank 2 Sensor
2) Harness connector for Oxygen Sensor (O2S) 2
behind Three Way Catalytic Converter (TWC) -
G131- (B2-S2) loose or corroded due to moisture
in the harness connector

- Check harness connector for tight fit
and contact corrosion, if necessary
reconnect and/or clean, installation
page 24
-1

Malfunction cause found: Yes
No

- Erase DTC memory, test drive and
check DTC memory again
MIL Status:
MIL lights up
immediately
Wiring connection to Oxygen Sensor (O2S) 2
behind Three Way Catalytic Converter (TWC) -
G131- (B2-S2) faulty, or sensor -G131- faulty

- Check O2S 2 behind three way
catalytic converter -G131- (B2-S2)
page 24
-53


Malfunction cause found: Yes
No

- Erase DTC memory, test drive and
check DTC memory again
For troubleshooting
Display group 041
Engine Control Module (ECM) -J192- faulty

- Replace and code engine control
module page 01
-265
erase DTC
memory and test drive check DTC
memory
Notes:
The malfunction "P0158 / 16542" is set 3 min after engine start, as soon as the O2S voltage is greater than 1.4 volts for
Pa
ge 67 of 366 On Board Dia
gnostic
(OBD
) - Multi
port Fuel In
jection
(MFI
)
11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU01.01.1

longer than 5 sec.
Pa
ge 68 of 366 On Board Dia
gnostic
(OBD
) - Multi
port Fuel In
jection
(MFI
)
11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU01.01.1

01-51

Output on GST and/or
on VAG 1551 scan tool Possible malfunction cause

Malfunction repair
P0161 / 16545
O2 Sensor Heater Circuit
Malfunction (Bank 2
Sensor 2) Harness connector for Oxygen Sensor
(O2S) heater -Z30- (B2-S2) loose or
corroded due to moisture in the harness
connector

- Check harness connector for tight fit and
contact corrosion, if necessary reconnect
and/or clean, installation page 24
-1

Malfunction cause found: Yes
No

- Erase DTC memory, test drive and
check DTC memory again
MIL Status:
MIL lights up immediately
Wiring connection for Oxygen Sensor
(O2S) heater -Z30- (B2-S2) or heater -Z30-
(B2-S2) faulty

- Check O2S heater -Z30- (B2-S2)
page 24
-55


Malfunction cause found: Yes
No

- Erase DTC memory, test drive and
check DTC memory again
For troubleshooting
Display group 040
Engine Control Module (ECM) -J192-
faulty

- Replace and code engine control
module page 01
-265
erase DTC
memory and test drive check DTC
memory
Notes:
The heater for O2S behind Three Way Catalytic Converter (TWC) is not switched on immediately at engine start, but only
when the calculated exhaust gas temperature exceeds 308 C (586 F) ( Read measuring value block, display group 42,
channel 1).
Pa
ge 69 of 366 On Board Dia
gnostic
(OBD
) - Multi
port Fuel In
jection
(MFI
)
11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU01.01.1

01-52

Output on GST and/or on
VAG 1551 scan tool Possible malfunction cause

Malfunction repair
P0170 / 16554
Fuel Trim Malfunction (Bank 1) Air leak in the area of the intake
manifold

- Find and repair leak

Malfunction cause found: Yes
No

- Erase DTC memory, test drive and
check DTC memory again

Oil dilution (fuel in the oil) because
of frequent cold starts or driving short
distances

- Check, if necessary do oil change
MIL Status:
MIL lights up after 2 Trips Malfunction cause found: Yes
No

- Erase DTC memory, test drive and
check DTC memory again

Mass Air Flow (MAF) sensor -G70-
supplies false signal

- Check Mass Air Flow (MAF) sensor -
G70- page 24
-81

For troubleshooting Display
groups 005, 007, 009 and 010
Malfunction cause found: Yes
No

- Erase DTC memory, test drive and
check DTC memory again

Oil burning with faulty piston

Repair Manual, 2.8 Liter V6 2V Engine
Mechanical, Engine Code(s): AFC, Repair Group 15
- Check compression pressure

Malfunction cause found: Yes

Pa
ge 70 of 366 On Board Dia
gnostic
(OBD
) - Multi
port Fuel In
jection
(MFI
)
11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU01.01.1

- Erase DTC memory, test drive and
check DTC memory again
Note:
The malfunction "P0170 / 16554" is set in the learning procedure as soon as the difference between a newly learned oxygen
sensor learning value and an optional stored oxygen sensor learning value is greater than 8%.
Pa
ge 71 of 366 On Board Dia
gnostic
(OBD
) - Multi
port Fuel In
jection
(MFI
)
11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU01.01.1

01-53

Output on GST and/or
on VAG 1551 scan tool
Possible malfunction
cause
Malfunction repair
P0171 / 16555
System too Lean (Bank
1) Malfunction P0174 /
16558
"System too Lean (Bank
2)"
Also in DTC memory
No

Yes

- If the fuel-air mixture for both cylinder banks is too lean, a
malfunction must be present that leads to incorrect mixture
formation for both banks (B1 and B2) Troubleshooting
according to Diagnostic Trouble Code (DTC) page 01
-57


Malfunction cause found:
Yes
No

- Erase DTC memory, test drive and check DTC memory
again
MIL Status:
MIL lights up after 2
Trips Leak in the exhaust
system for bank 1 up to
Heated Oxygen Sensor
(HO2S) -G39-

- Find and repair leak

Malfunction cause found:
Yes
No

- Erase DTC memory, test drive and check DTC memory
again

Leak in intake system

- Find and repair leak
Pa
ge 72 of 366 On Board Dia
gnostic
(OBD
) - Multi
port Fuel In
jection
(MFI
)
11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU01.01.1