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

01-175

Display
field Display on
VAG 1551 scan
tool Malfunction cause
Malfunction repair
2 Greater than
+14(HS)
and/or
greater than +
10(AT)
Idle Air Control (IAC) valve -N71- faulty
Electrical consumers on
Steering wheel at end stop
Driving mode selected (automatic transmission)
Intake manifold pump plugged in automatic transmission
EGR vacuum regulator solenoid valve -N18- open- Check DTC memory
page 01
-13
and/or display
group 018
- Switch electrical
consumers off
- Center steering wheel
- Move selector lever to P or
N
- Repair cause
- Check DTC memory
and/or display group 017,
display field 3
2 Less than -16
(HS)
and/or
less than -20
(AT)
Idle Air Control (IAC) valve -N71- faulty
Large air leak, manifold area, throttle stop not OK
Air leak on second stage of throttle - Check DTC memory
page 01
-13
and/or display
group 018
- Repair cause
3 Outside
tolerance range Only on vehicles with automatic transmission:

Display field 2 outside tolerance
If display field 2 is within tolerance, move selector lever to D Display field 2
- Check transmission
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and observe idle for approx. 1 min.; if display field 3 stays
outside tolerance, the transmission is hard to move
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01-176

Display
field Display on VAG 1551
scan tool Malfunction cause
Malfunction repair
4 Not 001 10
Closed Throttle Position (CTP) switch -F60 activated or faulty A/C compressor switched on Rear window heating switched on Driving mode selected (automatic
transmission) - Check and adjust -F60- page 24
-
73

- Switch A/C off
- Check A/C compressor shut-off
page 24
-90

- Move selector lever to P or N
Note:
Display field 4 (shift inputs) can be used to recognize whether the components described below are recognized by the Engine
Control Module (ECM) as switched on or off. Display group 023 gives an exact description of the shift inputs. 0
0
1

1
0
Meaning of 5-digit shift inputs

1 = Shifting Signal (0 = not active / 1 = active)

2 = Gear recognition signal (always "1" except that display = "0" for automatic transmission vehicles with
gear engaged)

3 = -----------

4 = Mechanical Closed Throttle Position (CTP) switch (1 = closed / 0 = open)

5 = A/C compressor OFF/ON (0 = off, 1 = on)

6 = Rear window heater signal (always "0" except for vehicles without A/C and with rear window heater
on)
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01-177
Display group 005 Display shows
Display/specified value
Designation
Basic setting 5
1 2 3 4 -25% to +25% 1 = Oxygen sensor learning value-idle (bank 1)
-25% to +25% 2 = Oxygen sensor learning value-partial throttle 1 (bank 1)
-25% to +25% 3 = Oxygen sensor learning value-partial throttle 2 (bank 1)
-25% to +25% 4 = Oxygen sensor learning value-partial throttle 3 (bank 1) Display group 006 Display shows
Display/specified value
Designation
Basic setting 6
1 2 3 4 -25% to +25% 1 = Oxygen sensor learning value-idle (bank 2)
-25% to +25% 2 = Oxygen sensor learning value-partial throttle 1 (bank 2)
-25% to +25% 3 = Oxygen sensor learning value-partial throttle 2 (bank 2)
-25% to +25% 4 = Oxygen sensor learning value-partial throttle 3 (bank 2) Notes:

Positive learning value (+ %): Mixture too lean, more fuel must be injected. (Programmed basic fuel injection time too
short, actual fuel injection time - % longer, so that = 1 is obtained).
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01-178
Test table display group 005 and/or display group 006 Display
fields Display on
VAG 1551
scan tool Malfunction cause
Malfunction repair
1, 2, 3, 4 Low oxygen
sensor learning
values
If first learning value in display field 1 is low, but
learning value in display fields 2, 3 and 4 normal:
oil dilution (large amount of fuel in the oil), fuel
injector leaks - Pull off cylinder block breather hose
and close
- If problem disappears after drive on
expressway and/or oil change
- Check fuel injector page 24
-29
If all four oxygen sensor learning values very low
overall:
- Fuel system pressure too high
- EVAP canister purge regulator valve -N80- open
continuously - Check system and residual pressure
page 24
-20

- Check -N80- page 24
-58
and/or
display group 009, display field 3
and/or display group 001, display field
2


Mass Air Flow (MAF) sensor -G70- faulty
Oxygen sensor (O2S) heating faulty or Heated
Oxygen Sensor (HO2S) dirty - Check MAF sensor -G70 page 24
-
81

- Check HO2S and O2S heating
page 24
-49
and/or display group 010,
display fields 1 and 2
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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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jection
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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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jection
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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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jection
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