1996 AUDI A4 sensor

24-36

- Compare display and specified values (display
fields 1 and 2):

Display fields

1 2 3 4
Display group 40: Oxygen Sensor (O2S) heating (before and after TWC)
Display
xx.x
Htg.bC.ON/Htg.bC.OFF
xx.x
Htg.aC.ON/Htg.aC.OFF
Indicates Resistance of O2S heater
(before TWC)
(B1-S1 and B2-S1) O2S heater ON
or
O2S heater OFF
(before TWC)
(B1-S1 and B2-S1) Resistance of O2S heater
(after TWC)
(B1-S2 and B2-S2) O2S heater ON
or
O2S heater OFF
(after TWC)
(B1-S2 and B2-S2)
Range
0.0 - 65.0
--- --- ---
Specified value
2.4 - 9.2
Htg.bC.ON --- ---

If not as specified page 24
-37
, Continuation
--- ---
If displayed values are OK (as specified):

-
Press button.
-
Press buttons -0- and -6- to select "End Output"
function 06, and press -Q- button to confirm
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24-37

Continuation

- Disconnect 4-pin connector (black) for
respective Heated Oxygen Sensor (HO2S).

If resistance is NOT OK: - Connect multimeter US1119 (Fluke 83 or equivalent) between HO2S
connector terminals 1 and 2, using VW1594 connector test kit.
- Measure resistance.

Specified value: 0.0-19.9 - Replace respective Heated Oxygen Sensor (HO2S).
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24-42

Oxygen Sensor (O2S) and Oxygen
Sensor (O2S) control behind TWC,
checking


Notes:

Connector for Oxygen Sensor (O2S) behind
Three Way Catalytic Converter (TWC) -G130-
(bank 1, sensor 2): 4-pin, green
Connector for Oxygen Sensor (O2S) 2 behind
Three Way Catalytic Converter (TWC) -G131-
(bank 2, sensor 2): 4-pin, brown
Component locations page 24
-1

Required special tools and test equipment

VAG1551 or VAG1552 Scan Tool (ST) with
VAG1551/3 adapter cable
VAG1598/22 test box
Multimeter US1119 (Fluke 83 or equivalent)
VW1594 connector test kit

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24-44

- Compare display and specified values (display
fields 1-4):

Display fields

1 2 3 4
Display group 36: Oxygen Sensor (O2S) behind Three Way Catalytic Converter (TWC), Banks 1, 2
Display x.xxx V Test OFF/Test
ON
B1-S2 ok
B1-S2 n.ok x.xxx V Test OFF/Test
ON
B2-S2 ok
B2-S2 n.ok
Indicates Voltage supply to O2S behind
TWC
(Bank 1, Sensor 2) Diagnostic status
Diagnostic result Voltage supply to O2S 2 behind
TWC
(Bank 2, Sensor 2) Diagnostic status
Diagnostic result
Range 0.000 - 1.000 V --- 0.000 - 1.000 V ---
Specified
value 0.000 - 1.000 V
(can oscillate slightly) B1-S2 OK 0.000 - 1.000 V
(can oscillate slightly) B2-S2 OK

If not as specified page 24
-45
, Continuation
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24-45

Continuation

- Road test to condition oxygen sensor (eliminate
possible contamination) and repeat test.
If the values are still NOT OK:

- Check Oxygen Sensor (O2S) heater(s) page
24
-52
.

- Briefly accelerate engine over 3000 RPM.
If the value in either display field 1 or field 3
remains constant:
page Page 24
-46
, Evaluation of display group
36.
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24-46
Evaluation of display group 36 Display group:
36


Display fields:
1, 3
Possible malfunction cause
Corrective action
approx. 0.435 V

Open circuit in wire -4- between oxygen sensor and
ECM - Check reference voltage page 24
-47
approx. 0.440 V

Open circuit in wire -3- between oxygen sensor and
ECM
approx. 1.085 V
Short circuit to B+ in wire -4- between oxygen sensor
and ECM - Check O2S wiring, bank 1, sensor 2
page 24
-48

- Check O2S wiring, bank 2, sensor 2
page 24
-50

approx. 0.000 V

Short circuit to Ground in wire -4- between oxygen
sensor and ECM
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24-47

Checking O2S reference voltage

- Disconnect 4-pin connector for respective
Oxygen Sensor (O2S) behind Three Way
Catalytic Converter (TWC).

If voltage is NOT OK:
If voltage is OK: - Connect multimeter US1119 (Fluke 83 or equivalent) between harness
connector terminals 3 and 4 (to ECM), using adapter cables from
VW1594 connector test kit.
- Start engine and measure voltage.
Specified value: 0.40 to 0.50 volts
- Switch ignition off.
- Check O2S wiring.

Bank 1, sensor 2 page 24
-48
.

Bank 2, sensor 2 page 24
-50
.
- Replace respective O2S behind TWC.
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24-48

Checking O2S wiring, bank 1, sensor 2

- Disconnect 4-pin connector (green) for Oxygen
Sensor (O2S) behind Three Way Catalytic
Converter (TWC) -G130-.

- Connect VAG1598/22 test box to ECM harness
connector page 01
-67
.

- Check wiring for open circuit between ECM/test box and 4-pin O2S
harness connector (to ECM).

Connector terminal 3 to ECM/test box socket 51
Connector terminal 4 to ECM/test box socket 52
Specified value: max. 1.5
- Check wiring for short circuits between terminals of 4-pin connector.

Connector terminal 4 to ECM/test box socket 51
Specified value:
- Check shielding wire for short circuit to sensor wires.

Connector terminal 4 to ECM/test box socket 14
Connector terminal 3 to ECM/test box socket 14
Specified value:
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