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

During "Basic Setting" function 04 with VAG 1551 scan tool and/or each time the DTC memory is erased, all learning
requirement displays are set to 0 in order to force new learning of the oxygen sensor learning values after the shop visit.
At each start, coolant temperature less than 40 C (104 F), the learning requirement is forced in all learning ranges. If there is a large learning value deviation (from the stored learning value to the newly learned value) in the learning
process, all learning requirement displays are reset to 0.
If there is successful learning, the learning requirement values of the respective learning ranges (display field 2) are set to 1.
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X
X
X
X
X
X
X
X
Meaning of 8-digit oxygen sensor learning requirement display

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)

8 = Partial throttle 3 (bank 2) Display value "0" = Request for new learning.
Display value "1" = Learning process ended.
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Display group 009 Display shows
Specified display value
Designation
Basic setting 9
1 2 3 4 ... % 1 = Oxygen sensor control (bank 1)
... % 2 = Oxygen sensor control (bank 2)
0 - 99% 3 = Duty cycle (triggering)-EVAP canister purge regulator valve -N80-
0% and/or greater than 95% 4 = Throttle angle - at idle: 0%; at wide open throttle: > 95% Note:
The oxygen sensor control should always be evaluated only after successful learning ( learning requirement display, display
group 007 and/or 008, display field 4) in both "Basic Setting" function 04 and "Read Measuring Value Block" function 08.
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Test table display group 009 Display fields
Display on VAG 1551 scan tool
Malfunction cause
Malfunction repair
1 -
- Display group 007, display field 1
2 -
- Display group 008, display field 13 -
- Note4 -
- Display group 003, display field 3
Notes on display field 3:

The evaporative emissions valve (EVAP canister valve) is closed during the learning process.
The effect of the EVAP canister can be evaluated by comparing the display value during "Basic setting" (EVAP canister
completely closed: 99%) and during "Read Measuring Value Block" (EVAP canister valve completely open: 0%).
You can switch back and forth between "Basic Setting" function 04 and "Read Measuring Value Block" function 08 by
pressing buttons -1- and -3- on VAG 1551 scan tool.
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Display group 010 Display
shows Specified display value
Designation
Basic setting
10
1 2 3 4 Difference between display values 1 and 2
less than 8% 1 = Total of oxygen sensor control (bank 1) and momentary
oxygen sensor learning value (bank 1)
2 = Total of oxygen sensor control (bank 2) and momentary
oxygen sensor learning value (bank 2)

At times greater than 0.6 V and/or less than
0.3 V (display must fluctuate) 3 = Voltage signal-bank 1 heated oxygen sensor 1
4 = Voltage signal-bank 2 heated oxygen sensor 1 Note:
The total of the oxygen sensor control and oxygen sensor learning value shows the total effect of the oxygen sensor control.
Bank differences can be evaluated directly by comparing display field 1 with display field 2.
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Test table display group 010 Display
fields Display on VAG 1551 scan tool
Malfunction cause
Malfunction repair
1/2 Difference between display value
1 (bank 1) and display value 2
(bank 2) greater than 8%
Spark plug faultyIntake air leak on one side Fuel injectors faulty - Repair cause
- Check DTC memory page 01
-13

and/or check fuel injectors page 24-
29


Heated Oxygen Sensor
(HO2S) faulty (dirty) - Check DTC memory page 01
-13

and/or display fields 3 and 4

Mechanical engine basic
setting (valve/camshaft
timing) not OK
Repair Manual, 2.8 Liter V6 2V
Engine Mechanical, Engine Code(s): AFC, Repair Group 13
- Check valve/camshaft timing
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Display
fields Display on VAG 1551 scan tool
Malfunction cause
Malfunction repair
3/4 Display does not fluctuate-constant
between 0.0 - 0.3 V and/or between
0.6 - 0.9 V
Fuel injector faulty- Check fuel injectors page 24
-29

Spark plug faultyLarge intake air leak Engine Coolant Temperature
(ECT) sensor -G62- faulty EVAP canister purge
regulator valve -N80- - Check spark plug
- Repair cause
- Check DTC memory page 01
-13

and/or check -G62-
- Check using output diagnostic test
mode page 01
-145
and/or check -
N80-

Heated Oxygen Sensor
(HO2S) -G39- faulty or dirty Oxygen Sensor (O2S) heater
-Z19- does not function - Check DTC memory page 01
-13

and/or check -G39-
- Check -Z19- page 24
-49

Fuel system pressure too
high or too low - Check fuel pressure regulator and
residual pressure page 24
-20


Constant 2.550 V Short to positive (B+) through:
Heated Oxygen Sensor
(HO2S) -G39- wiring Engine Control Module
(ECM) -J192- - Check -G39- page 24
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continued
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Display
fields Display on VAG 1551 scan tool
Malfunction cause
Malfunction repair
3/4
Constant value between 0.350 -
0.450 V Open circuit in:
Heated Oxygen Sensor (HO2S) -G39-
wiring Engine Control Module (ECM) -J192-- Check -G39- page
24
-49


Constant 0.000 V Short to ground in:
Heated Oxygen Sensor (HO2S) -G39-
wiring Engine Control Module (ECM) -J192-- Check -G39- page
24
-49


Notes on display field 4:
The display value at times must drop below 0.3 V
and exceed 0.6 V. Display values less than 0.40
V indicate lean condition; greater than 0.40 V
indicate rich condition.

HO2S voltage U (mV) vs. Lambda ( ) A - HO2S voltage (mV) high
Rich mixture (fuel excess or lack of air)
High CO value
B - Oxygen sensor probes voltage (mV) low
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Lean mixture (lack of fuel or excess air)
Low CO value
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