AUDI A4 1999 B5 / 1.G AFC Engine On Board Diagnostic Multiport Fuel Injection Workshop Manual

01-179

Display
fields Display on VAG
1551 scan tool Malfunction cause
Malfunction repair
1, 2, 3, 4 High oxygen
sensor learning
values
If learning value in display field 1 is low, but
learning value in display fields 2, 3 and 4
normal: air leak in manifold area possible
Fuel injector plugged - Repair cause
- Check fuel injector page 24
-29
If all four oxygen sensor learning values are very
high overall:
- Mass Air Flow (MAF) sensor -G70- faulty
- Fuel system pressure too low (fuel supply)
- Intake air leak between sensor -G70- and throttle
body
- Intake air leak in manifold gasket - Check MAF sensor -G70 page 24
-
81
and/or display group 001, display
field 2
- Check system and residual pressure
page 24
-20

- Repair cause


Oxygen sensor (O2S) heating faulty or Heated
Oxygen Sensor (HO2S) dirty - Check HO2S and O2S heating
page 24
-49
and/or display group 010,
display fields 1 and 2
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01-180
Notes on display groups 005 and 006:
If there are differences in oxygen sensor learning values ( display group 010, display fields 1 and 2 ) of more than 8%
between display group 005 (bank 1) and display group 006 (bank 2), the following malfunctions are possible:
Spark plugs faulty
Fuel injectors faulty (leaking, plugged)
Intake air leak on one side
Heated Oxygen Sensor (HO2S) faulty, dirty
Mechanical engine basic settings (valve/camshaft timing) not OK
If a difference of 9% is reached between the richest and leanest oxygen sensor learning value of one display group, further
learning will be discontinued in the two affected learning ranges ( display group 007 and/or 008). Learning requirements
display ( display groups 007 and/or 008) of these learning ranges cannot be 1.
If there is no power to the engine control module, all values are set back to 0.0%.
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01-181
Display group 007 Display shows
Display/specified value
Designation/diagnose
Basic setting 7
1 2 3 4 0.0 6.0%1)
1 = Oxygen sensor (O2S) control (bank 1)

XXXX 2 = Oxygen sensor learning range display

XXXXXXXX 3 = Oxygen sensor learning requirement diagnosis

XXXXXXXX 4 = Oxygen sensor learning requirement display
Display group 008 Display shows
Display/specified value
Designation/diagnose
Basic setting 8
1 2 3 4 0.0 6.0%1)
1 = Oxygen sensor (O2S) control (bank 2)

XXXX 2 = Oxygen sensor learning range display

XXXXXXXX 3 = Oxygen sensor learning requirement diagnosis

XXXXXXXX 4 = Oxygen sensor learning requirement display
1) Evaluate tolerance range of the oxygen sensor control only at idle during "Basic Setting" function 04, since the EVAP
canister can also be controlled during "Read Measuring Value Block" function 08
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01-182
Test table display group 007 and/or display group 008 Display
fields Display on VAG 1551
scan tool Malfunction cause
Malfunction repair
1 Outside tolerance range
Minus (-) display: engine too rich
Positive display: engine too lean ("+" is not
displayed)
Possible causes:
Effect: O2S control leans mixture Effect: O2S control enriches mixtureIntake air leakFuel injector faultySuccessful learning has not taken place (
display field 4) O2S learning value at stop ( display
groups 005 and/or 006)
- Wait 30 sec. until the display
has stabilized
2 - Notes
3 - Notes 4 - Notes
Notes on display field 1:
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Oxygen sensor control can basically be evaluated both in "Basic Setting" function 04 as well as in "Read Measuring Value
Block" function 08 only after successful learning ( learning requirement display). Oxygen sensor control shows momentary control status. After successful learning, ( learning requirement display),
values vary around 0.0 6.0%. If the learning process (display field 4) is ended and no value around 0.0 6.0% is
obtained, observe display group 010, display fields 3 and/or 4 and check control behavior of the two heated oxygen
sensors. During this process, the display values must at times drop below 0.3 V and exceed 0.6 V, otherwise check
oxygen sensor heating and the heated oxygen sensor.
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01-183
Notes on display field 1 (cont'd):
The oxygen sensor control stop evaluation is also done by the diagnosis only after successful learning learning
requirement display:
Control stop max.: + 32%
Control stop min.: - 87.5%
With values of more than 20% in "Basic Setting" function 04, the following malfunctions are possible: Intake air leaks
Engine damage (oil burning with faulty piston)
Notes on display field 2:
In display field 2 (learning range display), the momentary learning range (load status) is displayed. Only idle and partial
throttle learning ranges are displayed since, at wide open throttle, no learning takes place.
In order to reach the corresponding learning range (load status):
Idle: the vehicle should be allowed to run at idle (650-900 RPM)
Partial throttle 1, 2 or 3: during test drive (with second person), increase engine speed to 1500-3000 RPM and generate
load by lightly operating the brake
X
X
X
X
Meaning of 4-digit learning range display
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1 = Idle

2 = Partial throttle 1

3 = Partial throttle 2

4 = Partial throttle 3 Display value "0" = Engine speed and/or engine speed and load for this learning range not obtained.
Display value "1" = Engine speed and/or engine speed and load for this learning range obtained.
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01-184
Notes on display field 3

The oxygen sensor learning requirement diagnosis shows what oxygen sensor learning value was checked in the learning
process.
If diagnosis is successful, the corresponding value is set to "1", independently of whether the diagnosis was recognized as
OK or not OK.
If an "oxygen sensor learning requirement diagnosis" value is set to "1" in display field 3, but the corresponding value of
the "oxygen sensor learning requirement display" is not set to "1" in display field 4, the diagnosis was carried out but not
recognized as OK by the Engine Control Module (ECM). The " oxygen sensor learning requirement diagnosis" is now
continued.
The oxygen sensor learning requirement diagnosis is reset to "0" every time there is a start with a coolant temperature
less than 40 C (104 F).
X
X
X
X
X
X
X
X
Meaning of 8-digit oxygen sensor learning requirement diagnosis

1 = Idle (bank 1)

2 = Idle (bank 2)

3 = Partial throttle 1 (bank 1)

4 = Partial throttle 1 (bank 2)

5 = Partial throttle 2 (bank 1)

6 = Partial throttle 2 (bank 2)

7 = Partial throttle 3 (bank 1)
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8 = Partial throttle 3 (bank 2)

Display value "0" = Diagnosis not carried out yet.
Display value "1" = Diagnosis complete.
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01-185
Notes on display field 4
Display field 4 (learning requirement display) shows the learning range (display field 2) for which learning is required.
Requirement for learning:

No malfunction stored in DTC memory
Engine speed at idle 650-900 RPM and/or 1500-3000 RPM
Coolant temperature 80-110 C (176-230 F) (if learning does not start immediately after this requirement, step on the
throttle).
Learning is prohibited:

With uneven idle (hunting), during acceleration, at wide open throttle
If malfunctions are stored in the DTC memory (not with sporadic malfunctions)
If differences of 9% are obtained between the richest and leanest oxygen sensor learning value of one display group. If a
9% difference is obtained, continued learning of the learning range involved is discontinued. The learning requirement
display of this learning range can not be 1 display groups 005 and/or 006.
Learning starts 20 sec. after initiation of "Basic Setting" function 04 and/or 2 to 4 min. after each start at a which the coolant
temperature is less than 40 C (104 F). The following listing shows when the request for new learning (learning requirement) is forced:
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