fuel pressure AUDI A4 1999 B5 / 1.G AFC Engine On Board Diagnostic Multiport Fuel Injection User Guide

01-84

Output on GST and/or on
VAG 1551 scan tool Possible malfunction cause

Malfunction repair
P0453 / 16837
Evaporative Emission
Control System Pressure
Sensor High Input Harness connector on sensor for EVAP
canister -G172- (differential pressure sensor)
loose or corroded due to moisture in the
harness connector

- Check harness connector for tight fit
and contact corrosion, if necessary
reconnect and/or clean

Malfunction cause found: Yes
No

- Erase DTC memory, test drive and
after test drive, check DTC memory
again
MIL Status:
MIL lights up immediately Wiring connection to sensor for EVAP
canister -G172- (differential pressure sensor)
faulty, or sensor -G172- faulty

- Check sensor for EVAP canister -
G172- (differential pressure sensor)
page 24
-61


Malfunction cause found: Yes
No

- Erase DTC memory, test drive and
after test drive, check DTC memory
again
For troubleshooting
Display group 030
Engine Control Module (ECM) -J192- faulty

- Replace and code engine control
module page 01
-265
erase DTC
memory and test drive check DTC
memory
Note:
The malfunction "P0453 / 16837" is set as soon after engine start as the differential pressure sensor signal is greater than 5.0
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01-147

Rapid data transfer
Q
03 - Output Diagnostic Test Mode

Indicated on display
- Press -Q- button to confirm input.
Output diagnostic test mode Fuel Pump
(FP) Rela
y -J17

Indicated on display
The fuel pump relay must be triggers and the fuel pump must run; the
flowing noise at the fuel pressure regulator can be clearly heard.
- If fuel pump relay is not triggered, check control page 24
-24
.
-
Press button.
Output diagnostic test mode Idle Air Control
(IAC
) valve -N71

Indicated on display
This valve is triggered (clicks) until moving on to the next output by
pressing the button. - If the valve is not triggered (does not click), check -N71- page 24
-
37
.
-
Press button.
Output diagnostic test mode Intake manifold chan
ge-over valve -N156

Indicated on display
This valve is triggered (clicks) until you move on to the next output by
pressing the button. - If the valve is not triggered (does not click), check intake manifold
change-over valve -N156- page 24
-64
.
-
Press button.
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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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01-191

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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01-202
Display group 019 Display shows
Specified display value
Designation/diagnose
Basic setting 19
1 2 3 4 At idle: 1.5 - 3.5% 1 = Momentary engine power (internal computation value)
At 2500 RPM:
6.5 - 9.5%
At idle:
3.0 - 5.5 g/s 2 = Intake air quantity (via mass air flow sensor)
At 2500 RPM:
9.5 - 13.5 g/s
___ km/h 3 = Momentary vehicle speed display group 003, display field 4 _._ m/s 4 = Fuel injection time (average of all cylinders) Note on display field 1:
The momentary engine power is a control module-internal calculated value that is calculated from the amount of air taken in
under normal conditions (air pressure 1013 mbar, air temperature 20 C or 68 F).
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01-216
Display group 030 (EVAP system diagnosis)
Notes:

Display group 030 is only considered on vehicles with sensor for EVAP canister -G172-.
If the value of the EVAP throughput diagnosis is not set to "0" in display group 029, display field 1 during regeneration of
the readiness code, and/or there is a malfunction in DTC memory that relates to the EVAP system, display group 030 is
used to carry out a selective diagnosis.
Since the EVAP system is automatically shut off during "Basic Setting" function 04, display group 030 can only be
evaluated using "Read Measuring Value Block" function 08.
When diagnostic conditions are fulfilled, the Engine Control Module (ECM) checks the EVAP system at each start with the
help of the sensor for EVAP canister -G172-. The pressure between the EVAP canister and EVAP canister purge
regulator valve is measured with the sensor for EVAP canister -G172-.
The diagnostic conditions are only fulfilled during a drive of approx. 1-1/2 to 5 minutes at 80-100 km/h (50-63 mph) with
manual transmission in 4th or 5th gear, or automatic transmission selector lever in "D" position, preferably in 4th gear. If
the diagnostic conditions are fulfilled, the diagnosis is active. To get the diagnosis results, you have to drive approx. 1-1/2
to 5 minutes under the diagnostic conditions, while the pressure has to be measured with closed EVAP canister purge
regulator valve. First, the pressure must be measured with the valve closed. You can get the valve to close most easily by
having a preceding deceleration fuel shut-off. If there are problems in shutting the EVAP canister purge regulator valve by
deceleration fuel shut-off, it can also be shut by running display group 030 in "Basic Setting" function 04. Then the
pressure has to be measured again in "Read Measuring Value Block" function 08 with valve fully open.
The diagnosis is recognized as OK if the EVAP system low pressure measured in display field 1 is greater than the actual
calculated EVAP system minimum low pressure in display field 2.
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01-217

Display shows
Display/specified value
Designation/diagnosis
Basic setting 30
1 2 3 4 -- mbar 1 = Currently measured EVAP system under pressure
-- mbar 2 = Currently calculated EVAP minimum under pressure
0 - 99% 3 = Duty cycle (triggering) EVAP canister purge regulator valve
0% = completely open
99% = completely closed
X X X X X 4 = Diagnosis status and/or result Note on display field 2:
An under pressure calculated from the momentary throughput of the Mass Air Flow (MAF) sensor (intake air mass) is
displayed.
Notes on display field 4:
0 1 X X X = Diagnosis carried out, diagnosis OK
1 0 X X X = Diagnosis carried out, malfunction recognized, diagnosis is continued
The display positions marked with X do not have to be fulfilled to evaluate the diagnostic status and/or result.
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01-218

X
X
X
X
X
Meaning of 5-digit "Diagnostic Status and/or Result"

1 = Diagnostic conditions during test drive (approx. 1-1/2 to 5 minutes at 80-100 km/h (50-63 mph) with
manual transmission in 4th or 5th gear, or automatic transmission selector lever in "D" position, preferably
in 4th gear)
Manual transmission: 8 - 45%
Automatic Transmission: 8 - 20%
Value "0" = Diagnostic conditions not fulfilled
Value "1" = Diagnostic conditions fulfilled
Engine speed: 1600 RPM - 4500 RPM ( display group 003) Intake air through Mass Air Flow (MAF) sensor: 22 g/sec - 56 g/sec ( display group 019) Throttle angle: ( display group 003)

2 = Pressure measurement w/EVAP canister purge regulator valve completely closed
Value "0" = Pressure measurement not completed yet
Value "1" = Pressure measurement completed

3 = Pressure measurement w/EVAP canister purge regulator valve completely open
Value "0" = Pressure measurement not completed yet
Value "1" = Pressure measurement completed

4 = Diagnostic status
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