AUDI A4 2000 B5 / 1.G AWM Engine Oxygen Sensor Control Checking Owner's Guide
Manufacturer: AUDI, Model Year: 2000, Model line: A4, Model: AUDI A4 2000 B5 / 1.GPages: 46, PDF Size: 0.3 MB
Page 31 of 46
24-99
Display on VAS5051:
Checking oxygen sensor control after catalytic converter
Test requirement: - Do not continue test until indication in display field -2- has reached
"110" at least once.
Engine continues to run at 2600 RPM.
-
Click on - button
Display on VAS5051:
1 - Enter display group Max. input value = 255
- Select function "037" in button field -2- for "display group number 037"
and press -Q- button to confirm input.
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Page 32 of 46
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Display on VAS5051:
- Check oxygen sensor voltage in display field -2-.
- Check oxygen sensor correction value in display field -3- and
diagnostic result in display field -4-.
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Page 33 of 46
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Display fields
1 2 3 4
Display group 037: Diagnostic oxygen sensor control system
Display xxx %
x.xxx V
x.xx
---
Indicated Engine
load Oxygen sensor voltage
Bank 2, sensor 1 Oxygen sensor correction value
between bank 1, sensor 1 and
bank 1, sensor 2 Diagnostic condition
Functional
range
Test OFF
Test ON
System OK
System not OK
Specified
value 13 to 40
% 0.100 to 0.950 volts
smaller than 0.02 System OK
Note
If specified value is not
obtained: Evaluation
Page 24
-102
If "System not OK" is
displayed: Check DTC
memory Page 01
-12
Note for display field 2:
Oxygen sensor voltage bank 1, sensor 2 should remain fairly constant. Strong voltage fluctuations point to a damaged
catalytic converter.
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Page 34 of 46
24-102
Evaluation display group 037 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
-104
Open circuit in wire 3 between oxygen sensor
and control module
larger than
0.950 V Short circuit to B+ in wire 4 between oxygen
sensor and control module - Check oxygen sensor wiring, oxygen sensor after
catalytic converter Page 24
-105
smaller than
0.100 V
Short circuit to Ground (GND) in wire 4 between
oxygen sensor and control module
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Page 35 of 46
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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-.
Note:
If oxygen sensor voltage is OK and oxygen
sensor correction value is still above 0.02 ms,
even after a road test, this suggests aging of an
oxygen sensor before catalytic converter.
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Page 36 of 46
24-104
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 -1- (brown) to Oxygen Sensor
(O2S) behind Three Way Catalytic Converter (TWC) -G130-.
- Connect multimeter between terminal 3 and 4 for voltage
measurement.
- Switch ignition on.
Specification: 0.400 to 0.500 V
- Switch ignition off.
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Page 37 of 46
24-105
If specified value is not obtained:
- Check oxygen sensor wiring.
If specified value is obtained:
- Replace Oxygen Sensor (O2S) behind Three
Way Catalytic Converter (TWC) -G130-.
Checking oxygen sensor wires
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 -1- (brown) to Oxygen Sensor
(O2S) behind Three Way Catalytic Converter (TWC) -G130-.
- Connect VAG1598/31 test box at wiring harness to Engine Control
Module (ECM), do not connect ECM Page 24
-19
.
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Page 38 of 46
24-106
Electrical Wiring Diagrams, Troubleshooting & Component Locations
If wire connection is OK: - Check the following wire connections for open circuit.Harness connector
Terminal
VAG1598/31 test box
Socket
3 68
4 69
- Repair open circuit if necessary.- Check wires to each other for short circuit.
- Replace Engine Control Module (ECM) Page 24
-22
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Page 39 of 46
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Oxygen sensor heating, Oxygen Sensor
(O2S) Heater 1 -Z29- after catalytic
converter, checking
Special Tools and Equipment
VAG1526A
VAG1594A
VAG1598/31
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Page 40 of 46
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Test requirements:
Coolant Temperature at least 80 C.
Fuse for oxygen sensor heating OK
Electrical Wiring Diagrams, Troubleshooting &
Component Locations
Test sequence
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 -1- (brown) to Oxygen Sensor
(O2S) behind Three Way Catalytic Converter (TWC) -G130-.
If specified value is not obtained: - Connect multimeter between terminal 1 and 2 for resistance
measurement.
Specified value at room temperature: 6.4 to 47.5
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