AUDI A6 1999 C5 / 2.G ATQ Engine Oxygen Sensor Control Checking

24-85
Evaluation display group 033 Display field: 1 / 3
Possible cause
Corrective action
Values in range:
-10.0 to -25.0 %
Oxygen sensor heating faulty- Check oxygen sensor heating Page
24
-116

or
Values in range:
Open circuit in wires between oxygen sensor
and control module - Check primary voltage Page 24
-89
10.0 to 25.0 %
or
Value does not fluctuate
by at least 2 %
Short circuit to Ground (GND) or B+ between
oxygen sensor and control module - Check oxygen sensor wires bank 1
Page 24
-90

- Check oxygen sensor wires bank 2
Page 24
-91



False air in intake area- Check intake system for leaks and
repair false air Page 24
-64



Fuel pressure too low or too high- Check fuel pressure regulator Page
24
-30



Fuel return line is kinked or clogged- Check fuel return line.
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- Press -C- button.

- Press buttons -0-, -3- and -2- to select "display
group number 032" and press -Q- button to
confirm input. System in Basic Setting 32
1
2
3
4

When indicated on display:
- Check oxygen sensor control in display fields 1 to 4:

Display fields

1 2 3 4
Display group 032: Oxygen sensor adaptation values before catalytic converter
Display
xx.x %
xx.x %
xx.x %
xx.x %
Indicated
Oxygen sensor
adaptation value
Bank 1 at idle
(additive) Oxygen sensor adaptation
value bank 1 at partial
throttle
(multiple) Oxygen sensor
adaptation value
Bank 2 at idle
(additive) Oxygen sensor adaptation
value bank 2 at partial
throttle
(multiple)
Functional
range -25.0 to 25.0 %
-25.0 to 25.0 %
-25.0 to 25.0 %
-25.0 to 25.0 %

Specified
value -10.0 to 10.0 %
can fluctuate
slightly -10.0 to 10.0 %
can fluctuate slightly -10.0 to 10.0 %
can fluctuate
slightly -10.0 to 10.0 %
can fluctuate slightly
Notes
If specified value is not obtained Page 24
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24-87
Evaluation display group 032 Display field:
1 / 3 or 2 / 4
Possible cause
Corrective action
Oxygen sensor
adaptation value in
range:
-10.0 to .-25.0 %
Oil thinning- Oil change or perform swift country road
test

High oil consumption

Mass Air Flow (MAF) sensor faulty- Mass Air Flow (MAF) sensor, checking

Page 24
-56



Evaporative Emission (EVAP) canister purge
regulator valve remains stuck in open position - Check Evaporative Emission (EVAP)
Canister Purge Regulator Valve Page 24
-
128



Fuel pressure too high- Check fuel pressure regulator Page 24
-
30



Fuel return line is kinked or clogged.- Check fuel return line.

Fuel injector does not close- Check fuel injectors Page 24
-36Pa
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24-88
Evaluation display group 032 Display field:
1 / 3 or 2 / 4
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
-64
.


Fuel pressure too low- Check fuel pressure regulator Page 24
-30


Mass Air Flow (MAF) sensor faulty- Mass Air Flow (MAF) sensor, checking

Page 24
-56



Oxygen sensor heating faulty
Oxygen sensor faulty- Check oxygen sensor heating Page 24
-116


Fuel injector does not open or opens
only partially - Check fuel injectors Page 24
-36


Evaporative Emission (EVAP) Canister
Purge Regulator Valve sticks - Check Evaporative Emission (EVAP) Canister
Purge Regulator Valve Page 24
-128



Ignition coil or spark plug faulty- Check ignition coils Page 28
-7
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24-89

Checking primary voltage
Component location of harness connectors
Overview of component locations, page Page
24
-5

Note:
Coolant reservoir screws must be removed and
coolant reservoir must be placed to side in order
to access this harness connector. The coolant
hoses can remain connected.

Test requirement:

Fuse for oxygen sensor are OK

- Disconnect 4-pin harness connector leading to
respective oxygen sensor.

If specified value is not obtained: - 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 wires Bank 1, page Page 24
-90
or Bank Pa
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2, page Page 24
-91
.
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24-90

Check oxygen sensor wires bank 1 for Heated
Oxygen Sensor (HO2S) 2 -G39-.
Component location of harness connectors
Overview of component locations, page Page
24
-5

- Disconnect black 4-pin harness connector to
bank 1 Heated Oxygen Sensor (HO2S) -G39-.

- Connect VAG1598/31 test box at wiring harness
to ECM, do not connect ECM Page 24
-17
.

- Check the 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.Harness connector
Terminal
VAG1598/31 test box
Socket
4 51
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If no malfunctions are found in wires:
Check oxygen sensor wires bank 2 for Heated Oxygen Sensor
(HO2S) 2 -G108-.
Component location of harness connectors Overview of component
locations, page Page 24
-5 - Check shielded wire for short circuit to sensor wires.
Harness connector
Terminal
VAG1598/31 test box
Socket
3 32
4 32
- Replace Engine Control Module (ECM) Page 24
-21
.
- Disconnect black 4-pin harness connector to bank 2 Heated Oxygen
Sensor (HO2S) 2 -G108-.
- Connect VAG1598/31 test box at wiring harness to ECM, do not
connect ECM Page 24
-17
.
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If no malfunctions are found in wires: - Check the following wire connections for open circuit.Harness connector
Terminal
VAG1598/31 test box
Socket
3 12
4 13
- Repair open circuit if necessary.
- Check wires to each other for short circuit.Harness connector
Terminal
VAG1598/31 test box
Socket
4 12
- Check shielded wire for short circuit to sensor wires.Harness connector
Terminal
VAG1598/31 test box
Socket
3 32
4 32
- Replace Engine Control Module (ECM) Page 24
-21
.
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24-93

Oxygen sensor aging (oxygen sensor
before catalytic converter), checking


Special Tools and Equipment

VAG1788/10 RPM adjuster

Test requirement:
VAS5051 with VAG5051/1
orVAG1551 with VAG1551/3BCoolant temperature at least 80 C Display group 4, display field 3
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