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

01-58


Malfunction on spark plug(s) or ignition cable(s)
of Bank 1

- Spark harness connector loose or faulty check- Check ignition cable for damage (e.g. cracks, traces of
burns, worn places)
- Check face side of spark plugs

Malfunction cause found: Yes
No

- Erase DTC memory, test drive and check DTC memory

Malfunction in the fuel injectors in Bank 2
because of
- Resistance in the fuel injector connectors
- Fuel injector that is dirty, faulty or has carbon
deposits

- Check harness connector on fuel injector for tight fit
- Check fuel injection quantity and for leaks page 24
-33

Malfunction cause found: Yes
No

- Erase DTC memory, test drive and check DTC memory

Intake valves have carbon deposits

- Check intake valves for carbon deposits, if necessary clean
valves

Malfunction cause found: Yes
No

- Erase DTC memory, test drive and check DTC memory

Continue Troubleshooting per Diagnostic Trouble Code (DTC) table page 01
-16

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Notes:
If the malfunction "P0174 / 16558" is set, the oxygen sensor control has exceeded the learning value limit in the "rich"
direction, but the (HO2S) still recognizes "mixture too lean".
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01-59

Output on GST and/or on VAG
1551 scan tool Possible malfunction
cause
Malfunction repair
P0175 / 16559
System too Rich (Bank 2) Malfunction P0172 /
16556
"System too Rich (Bank 1)"
Also in DTC memory
No
Yes

- Fuel pressure too high. Check system
pressure and residual pressure page 24
-20

Malfunction cause found:
Yes
No

- Erase DTC memory, test drive and check
DTC memory again
MIL Status:
MIL lights up after 2 Trips Fuel injector (Bank 2)
does not close or leaks

- Check fuel injection quantity and for leaks
page 24
-33

For troubleshooting Display
groups 006, 008, 009 and 010
Malfunction cause found:
Yes


- Erase DTC memory, test drive and check
DTC memory again
Notes:
If the malfunction "P0175 / 16559" is set, the oxygen sensor control has dropped below the learning value limit in the "lean"
direction, but the (HO2S) still recognizes "mixture too rich".
Pa
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01-60

Output on GST and/or on
VAG 1551 scan tool Possible malfunction
cause
Malfunction repair
P0171 / 16555
System too Lean (Bank 1) Malfunction P1250 /
17658 "Fuel Level Too
Low" also in DTC memory
No
Yes

- For malfunctions that can be caused by fuel problems
(e.g. fuel system too lean), the malfunction "Fuel Level
Too Low" is also set if there is less than 12 liters (12.7 qt.)
fuel in the tank check tank level and fill tank if necessary
P0174 / 16558
System too Lean (Bank 2) Malfunction cause found:
Yes
No

- Erase DTC memory, test drive and check DTC memory
again
MIL Status:
MIL lights up after 2 Trips Large air leak quantity
in intake system to Mass
Air Flow (MAF) sensor -
G70-

- Determine cause of air leak and repair
For troubleshooting
Display groups 005, 006,
007, 008, 009 and 010
Malfunction cause found:
Yes
No
Continued next page

- Erase DTC memory, test drive and check DTC memory
again
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01-61


Fuel system pressure too low because of:
- Leaks in the area of the fuel lines or the fuel distributor strip
- Vacuum line to the fuel pressure regulator or fuel pressure
regulator faulty
- Fuel filter plugged
- Fuel pump delivery quantity too low

- Check system pressure and residual pressure
page 24
-20


Malfunction cause found: Yes
No

- Erase DTC memory, test drive and check DTC
memory

EVAP canister purge regulator valve -N80- sticks
mechanically in closed position

- Check EVAP canister purge regulator valve -
N80- page 24
-58


Malfunction cause found: Yes


- Erase DTC memory, test drive and check DTC
memory
Notes:
If the malfunctions "P0171 / 16 555 and P0174 / 16558"are set, is set, the oxygen sensor control has exceeded the learning
value limit in the "rich" direction, but the (HO2S) still recognizes "mixture too lean".
Pa
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) - Multi
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jection
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)
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yp
e=re
pair&id=AUDI.B5.FU01.01.1

01-62

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

Malfunction repair
P0300 / 16684
Random Misfire Detected
_______________________
P0301 / 16685
Cylinder 1 Misfire Detected Malfunction P1250 / 17658 "Fuel
Level Too Low" also in DTC memory
No
Yes

- For malfunctions that can be caused by
fuel problems (e.g. fuel system too lean),
the malfunction "Fuel Level Too Low" is
also set if there is less than 12 liters (12.7
qt.) fuel in the tank check tank level and
fill tank if necessary
_______________________
P0302 / 16686
Cylinder 2 Misfire Detected Malfunction cause found: Yes
No

- Erase DTC memory, test drive and check
DTC memory again
_______________________
P0303 / 16687
Cylinder 3 Misfire Detected
_______________________ Are other Diagnostic Trouble
Codes (DTC) present in the DTC
memory (e.g fuel injector, heated
oxygen sensor probes, fuel system
etc.) when combustion misfiring is
recognized
No Yes

- The combustion misfiring that has been
recognized is a resulting malfunction from
the stored Diagnostic Trouble Codes (DTC)
First repair this malfunction according to
Diagnostic Trouble Code (DTC) table
MIL Status:
MIL lights up or blinks
For troubleshooting Display
groups 031, 038, 039
Malfunction cause found: Yes
No
Continued next page

- Erase DTC memory, test drive and check
DTC memory again
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01-63


Has combustion misfiring only been recognized on one
or two cylinders (2/4 or 3/5 or 1/6)?
No
Yes

- Spark harness connector loose or faulty check- Check ignition cable for damage (e.g. cracks, traces
of burns, worn places)
- Check face side of spark plug
- Fuel injector of the cylinder faulty; check fuel injector
page 24
-29


Malfunction cause found: Yes
No

- Erase DTC memory, test drive and check DTC
memory again

Has combustion misfiring occurred on two cylinders
(2/4 or 3/5 or 1/6)?
No Yes

- Common ignition coil of both affected cylinders
faulty, check ignition coil page 28
-16


Malfunction cause found: Yes
No
Continued next page

- Erase DTC memory, test drive and check DTC
memory
Pa
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) - Multi
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jection
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)
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01-64


Combustion misfiring has been stored in the DTC
memory for several or all cylinders

- Leaks in intake system check intake system for air
leaks - Fuel pressure not OK Check system and residual
pressure page 24
-20

- Exhaust gas recirculation too high check EGR
system hoses and components - Carbon deposits on fuel injectors check- Carbon deposits on intake valves

Malfunction cause found: Yes


- Erase DTC memory, test drive and check DTC
memory
Notes:

The malfunction "P0300 / 16684" is set as soon as combustion misfiring has been recognized in more than one cylinder.
If there is combustion misfiring with low misfiring rate, the MIL is only set after two successive trips without preceding cold
start and the malfunction occurring.
Combustion misfiring with high misfiring rate is displayed immediately by the MIL blinking, since the Three Way Catalytic
Converter (TWC) can be damaged. In this case, driving should be continued with reduced power and the malfunction
should be repaired as quickly as possible.
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port Fuel In
jection
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)
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01-65

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

Malfunction repair
P0300 / 16684
Random Misfire Detected
_______________________
P0304 / 16688
Cylinder 4 Misfire Detected Malfunction P1250 / 17658 "Fuel
Level Too Low" also in DTC
memory
No
Yes

- For malfunctions that can be caused by
fuel problems (e.g. fuel system too lean), the
malfunction "Fuel Level Too Low" is also set
if there is less than 12 liters (12.7 qt.) fuel in
the tank check tank level and fill tank if
necessary
_______________________
P0305 / 16689
Cylinder 5 Misfire Detected Malfunction cause found: Yes
No

- Erase DTC memory, test drive and check
DTC memory again
_______________________
P0306 / 16690
Cylinder 6 Misfire Detected
_______________________ When combustion misfiring is
recognized, are there other
Diagnostic Trouble Codes (DTC)
(e.g. fuel injector, Oxygen Sensor
Proben, Fuel system etc.) in DTC
memory
No Yes

- The combustion misfiring that has been
recognized is a resulting malfunction from
the stored Diagnostic Trouble Codes (DTC)
First repair this malfunction according to
Diagnostic Trouble Code (DTC) table
MIL Status:
MIL lights up or blinks
For troubleshooting Display
groups 031, 038, 039
Malfunction cause found: Yes
No
Continued next page

- Erase DTC memory, test drive and check
DTC memory again
Pa
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(OBD
) - Multi
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jection
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)
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yp
e=re
pair&id=AUDI.B5.FU01.01.1

01-66


Has combustion misfiring been recognized on only
one or two cylinders (2/4 or 3/5 or 1/6)?
No
Yes

- Spark harness connector loose or faulty check- Check ignition cable for damage (e.g. cracks, traces
of burns, worn places)
- Check face side of spark plug
- Fuel injector of the cylinder faulty Check fuel
injector page 24
-29


Malfunction cause found: Yes
No


- Erase DTC memory, test drive and check DTC
memory again

Has misfiring occurred on two cylinders (2/4 or 3/5 or
1/6)?
No Yes

- Common ignition coil for the two cylinders affected
faulty, check ignition coil page 28
-16


Malfunction cause found: Yes
No
Continued next page

- Erase DTC memory, test drive and check DTC
memory
Pa
ge 90 of 366 On Board Dia
gnostic
(OBD
) - Multi
port Fuel In
jection
(MFI
)
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yp
e=re
pair&id=AUDI.B5.FU01.01.1