1995 AUDI A4 check engine

01-172

Display
field Display on VAG
1551 scan tool Malfunction cause
Malfunction repair
3 Greater than 0%
at idle
Throttle position sensor -G69- faultyAccelerator pedal cable adjustmentThrottle sticks
Repair Manual, 2.8 Liter V6 2V Engine
Mechanical, Engine Code(s): AFC, Repair Group 20
- Check DTC memory page 01
-13
and/or
display group 002
- Adjust accelerator pedal cable:- Repair cause
At wide open
throttle less than
95%
Throttle position sensor -G69- faultyAccelerator pedal cable adjustment Throttle position sensor -G69- incorrectly
adjusted
Repair Manual, 2.8 Liter V6 2V Engine
Mechanical, Engine Code(s): AFC, Repair Group 20
- Check DTC memory page 01
-13
and/or
display group 002
- Adjust accelerator pedal cable:- Check and adjust sensor -G69- Repair
Group 24
4 No display
Wiring connection between instrument
panel insert and Engine Control Module
(ECM) -J192- faulty Open circuit or short between Vehicle
Speed Sensor (VSS) -G68- and -J192- - Electrical Wiring Diagrams, - Check vehicle speed signal page 24
-97
- Check -G68- check vehicle speed
sensor:
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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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01-184
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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01-190
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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01-191

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
-49Pa
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01-192

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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01-198
Display groups 015 and 016
Notes on display fields 2, 3 and 4:
If there is a difference of more than a factor of 3 between the lowest and the highest knock sensor signal in one display group,
the following malfunction is possible:

Corrosion on the harness connector
If there are differences of more than 50% in knock sensor signal between display group 015 (cylinders 1 to 3) and display
group 016 (cylinders 4 to 6), the following malfunctions are possible:
Corrosion on the harness connector
Open circuit
Knock sensor faulty
If no malfunctions are found during the electrical testing of the knock sensor, the wiring and the connections, the engine
should be checked for loose subassemblies or engine damage (e.g. oil burning due to faulty piston) Display groups 013
and/or 014.
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01-199
Display group 017
Note:
If in display group 029, display field 1, the value of the EGR system throughput diagnosis is not set to "0" during the
regeneration of the "readiness code," and/or a malfunction relating to the exhaust system is stored in the DTC memory,
display group 017 is used to carry out a selective diagnosis.
During cold start at idle, -10 C to 30 C (14 to 86 F), and during "Basic Setting" function 04, no exhaust gas recirculation
takes place. Since exhaust gas recirculation is switched off automatically during "Basic Setting" function 04, diagnosis of EGR
throughput is evaluated only in "Read Measuring Value Block." function 08. If diagnostic conditions are fulfilled, the Engine Control Module (ECM) checks the flow through the EGR system after each
start. The diagnostic conditions are only reached during a trip at 80-100 km/h (50-63 mph) in 4th or 5 gear and/or with selector
lever in the "D"position, preferably in 4th gear position. If the diagnostic conditions are fulfilled, the diagnosis is active. In order
to get a diagnostic result, the vehicle must be driven approx. 1-1/2 to 5 minutes under the diagnostic conditions. However, the
diagnosis is only considered OK when the EGR temperature (display field 4) is greater than 50 C (122 F) during the reading
time (display field 2). Diagnosis of the EGR flow (exhaust gas recirculation quantity) is active as soon as the following diagnostic conditions are
fulfilled:

Coolant temperature: greater than 8 C (46 F) ( display group 001) Vehicle speed: constant drive
Engine speed: 2000-3000 RPM ( display group 003) Engine load: 30-60%
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