low AUDI A4 1999 B5 / 1.G ATW Engine Oxygen Sensor Control Workshop Manual
[x] Cancel search | Manufacturer: AUDI, Model Year: 1999, Model line: A4, Model: AUDI A4 1999 B5 / 1.GPages: 37, PDF Size: 0.28 MB
Page 8 of 37
24-78
Display group 032 Display field: 1 / 2
Possible cause
Corrective action
Oxygen sensor adaptation
value in range: -10.0 to -25.0
%
Leak in intake area (pressure side between
turbocharger and intake manifold) - Check intake system for leaks and
repair false air Page 24
-68
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
-60
Evaporative Emission (EVAP) canister
purge regulator valve remains stuck in open
position - Check Evaporative Emission (EVAP)
canister purge regulator valve Page
24
-107
Fuel pressure too high- Check fuel pressure regulator Page
24
-33
Fuel injector does not close- Check fuel injectors Page 24
-38
.
Oxygen sensor heating faultyOxygen sensor faulty- Check oxygen sensor heating Page
24
-99
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Page 9 of 37
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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Page 12 of 37
24-82
- 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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Page 17 of 37
24-87
Heated Oxygen Sensor (HO2S) and
oxygen sensor control after Three Way
Catalytic Converter (TWC), checking
Note:
Oxygen sensor control behind catalytic converter
is superior to oxygen sensor control before
catalytic converter and is responsible for control
correction.
It corrects slight changes in the mixture (i.e. enrichment) via the oxygen
sensor before catalytic converter by holding oxygen sensor control before
catalytic converter at its higher or lower point for a specific time (dwell
time). If this time is in the positive range (i.e. 50 ms), mixture is shifted in
the -enrich- direction. If it is in the negative range (e.g. -50 ms), mixture
will be shifted in the -lean- direction.
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Page 23 of 37
24-93
Display fields
1 2 3 4
Display group 037: Diagnostic oxygen sensor control system
Display xxx %
x.xxx volts
xxx ms
---
Indicated Engine
load Oxygen sensor voltage
Bank 2, sensor 1 Dwell time, oxygen sensor control
before catalytic converter, bank 1 Diagnostic condition
Functional
range
Test OFF
Test ON
System OK
System not OK
Specified
value 15 to 33
% 0.100 to 0.900 V
-150 to 150 ms System OK
Note
If specified value is not
obtained: Evaluation display
field 2 Page 24
-94
If value climbs to above 300 ms,
this indicates a leaking exhaust
system or faulty oxygen sensor If "SYST not OK" is
displayed: Check DTC
memory Page 01
-16
Note for display field 3:
Oxygen sensor control behind catalytic converter is superior to oxygen sensor control before catalytic converter and is
responsible for control correction. It corrects slight changes in the mixture (i.e. toward rich or lean) due to the oxygen sensor
before catalytic converter by holding oxygen sensor control before catalytic converter at its higher or lower point for a specific
time (dwell time). If this time is in the positive range (i.e. 50 ms), mixture is shifted in the -enrich- direction. If this time is in the
negative range (i.e. -50 ms), mixture is shifted in the -lean- direction.
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Page 27 of 37
24-97
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
.
- Check following wire connections for open circuit.Harness connector
Terminal
VAG1598/31 test box
Socket
3 68
4 69
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Page 32 of 37
24-102
- Start engine.
Specification: approx. battery voltage,
possibly fluctuating
Note:
At certain operating points, the ECM "pulses"
the Ground (GND) for oxygen sensor heating.
This means that the Ground (GND) is
constantly switched on and off at these points.
It is therefore possible that the voltage
displayed on the tester will fluctuate.
When the ECM switches oxygen sensor heating
on and off can be observed, if necessary, via
the function "read measuring value block"
display group number 041.
If there is no voltage:
- Connect multimeter for voltage measurement as
follows:
Harness connector
Terminal
Measure to
1 (B+) Vehicle Ground (GND)
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Page 34 of 37
24-103
If there is no voltage again:
- Check wire connection from terminal 1 of
connector to Fuel Pump (FP) relay via fuse for
open circuit:
Electrical Wiring Diagrams, Troubleshooting &
Component Locations If voltage supply is OK:
If there is no voltage: - Connect multimeter for voltage measurement as follows:Harness connector
Terminal
Measure
to
2 (Ground -GND- activation of Engine Control Module -
ECM-) B+
- Start engine.
Specification: approx. battery voltage, possibly fluctuating
- Switch ignition off.
- 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 35 of 37
24-104
Oxygen Sensor (O2S) heater -Z19- for oxygen sensor before catalytic
converter:
Oxygen sensor heater 1 -Z29- for oxygen sensor behind catalytic
converter:
If wire connection is OK, but there is no Ground (GND) supply for oxygen
sensor heating: - Check following wire connection for open circuit:Harness connector
Terminal
VAG1598/31 test box
Socket
2 5
Harness connector
Terminal
VAG1598/31 test box
Socket
2 63
- Repair open circuit if necessary.
- Replace Engine Control Module (ECM) Page 24
-23
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