1998 AUDI A4 sensor

24-79
Display group 032 Display field: 1 / 2
Possible cause
Corrective action
Oxygen sensor adaptation
value in range:10.0 to 25.0 %
False air in intake area- Check intake system for leaks and repair
false air Page 24
-68


Fuel pressure too low- Check fuel pressure regulator Page 24
-
33


Mass Air Flow (MAF) sensor faulty- Mass Air Flow (MAF) sensor, checking
Page 24
-60


Oxygen sensor heating faultyOxygen sensor faulty- Check oxygen sensor heating Page 24
-
99


Fuel injector does not open or opens
only partially - Check fuel injectors Page 24
-38
.

Evaporative Emission (EVAP)
Canister Purge Regulator Valve sticks - Check Evaporative Emission (EVAP)
canister purge regulator valve Page 24
-
107

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24-80
Evaluation display group 033 Display field:
2
Possible cause
Corrective action
constant about
0.450 V
Open circuit in wire 4 between oxygen sensor
and control module - Check primary voltage Page 24
-80


Open circuit in wire 3 between oxygen sensor
and control module
constant about
0.200 V Oxygen sensor faulty- Replace oxygen sensor
larger than
1.100 V Short circuit to B+ in wire 4 between oxygen
sensor and control module - Check oxygen sensor wiring, oxygen sensor
before catalytic converter Page 24
-81

smaller than
0.150 V
Short circuit to Ground (GND) in wire 4 between
oxygen sensor and control module

Checking primary voltage

Note:
Coolant reservoir screws must be removed and coolant reservoir must be
placed to side in order to access the harness connector. The coolant hoses
can remain connected. - Disconnect 4-pin harness connector -2- (black) to Heated Oxygen Sensor
(HO2S) -G39- before catalytic converter.
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If specified value is not obtained:
If specified value is obtained:
Checking oxygen sensor wires - Connect multimeter between terminal 3 and 4 for voltage
measurement.
- Switch ignition on.

Specification: 0.400 to 0.500 V
- Switch ignition off.
- Check oxygen sensor wiring.
- Replace Heated Oxygen Sensor (HO2S) -G39-.

Note:
Coolant reservoir screws must be removed and coolant reservoir must be
placed to side in order to access the harness connector. The coolant
hoses can remain connected. - Disconnect 4-pin harness connector -2- (black) to Heated Oxygen
Sensor (HO2S) -G39- before catalytic converter.
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- Connect VAG1598/31 test box at wiring harness
to Engine Control Module (ECM), do not connect
ECM Page 24
-19
.

If wire connection is OK: - Check following wire connections for open circuit.Harness connector
Terminal
VAG1598/31 test box
Socket
3 51
4 70
- Repair open circuit if necessary.
- Check wires to each other for short circuit.
- Replace Engine Control Module (ECM) Page 24
-23
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Oxygen sensor aging (oxygen sensor
before catalytic converter), checking


Special tools and equipment

VAG1788/10 RPM adjuster

or
Test requirement:
VAS5051 with VAG5051/1VAG1551 with VAG1551/3ACoolant Temperature at least 80 C.
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Test sequence

- Connect VAS5051 tester or VAG1551 scan tool
and select control module for engine electronics
using "address word" 01 Page 01
-10
. Engine
must run at idle.
Rapid data transfer
HELP
Select function XX

When indicated on display
- Press buttons -0- and -4- to select "Initiate basic setting" and press -Q-
button to confirm input.
Basic Settin
g
Q
Enter displa
y group number XXX

When indicated on display
- Press buttons -0-, -3- and -4- to select "display group number 034" and
press -Q- button to confirm input.
System in basic setting 34
1
2
3
4

When indicated on display
Note:
This process can take a few minutes. - Use VAG1788/10 RPM adjuster to adjust engine speed to between
1800 and 2200 RPM.
- Check specified value in display field 4:
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Display fields

1 2 3 4
Display group 034: Diagnostic oxygen sensor aging
Display xxxx/min
xxx C
x.x s
---
Indicated Engine speed
(RPM) Exhaust
temperature Period duration Oxygen sensor before
Catalytic converter Diagnostic
condition
Functional
range

Test OFF
Test ON
B1-S2 OK
B1-S2 not OK
Specified
value 1800 to 2200
RPM more than 350 C
0.0 to 1.0 s B1-S2 OK
Note


If specified value is not obtained Continuation, Page 24
-
86

Note for display field 2:
Calculated value from engine speed and engine load.
Note for display fields 3 and 4:
Period duration is the time between two oxygen sensor voltage jumps (e.g. rich - lean - rich) and is therefore a measurement
of the aging condition of the oxygen sensor. If the specified time is exceeded, display field 4 will indicate = B1-S1 not OK.
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Continuation
If specified value in display field 3 and 4 is not
obtained:

- Road test vehicle in order to free oxygen sensor
of possible residue and repeat test.
If specified value in display field 3 and 4 is not
obtained, even after road test:

- Replace Heated Oxygen Sensor (HO2S) -
G39-.
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