fuel AUDI A4 1998 B5 / 1.G APB Engine Oxygen Sensor Control Checking Workshop Manual
Page 11 of 61
24-89
If the specified values in display fields 1
and/or 3 do not match the specifications, or if
the readout does not fluctuate by at least 2
%:
- Check oxygen sensor heater Page 24
-114
.
- Check oxygen sensor signal wire and activation
Page 24
-122
.
- Check intake system for leaks and eliminate
false air Page 24
-76
.
- Check fuel pressure regulator Page 24
-33
.
- Fuel return line kinked or plugged.
-
Press button.
- Press button -0- and -6- to select function "End
Output" and confirm with -Q- button.
- Switch ignition off.
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Page 12 of 61
24-90
Evaluation display group 032 Display group 32
Display fields: 1/3
Possible cause
Corrective action
Oxygen sensor adaptation
values in range:
-4.0 to -25.0 %
Oil thinning- Carry out oil change or carry out
road test on highway
Display fields: 2/4
High oil consumption
Oxygen sensor adaptation
values in range:
-4.0 to -25.0 % Mass Air Flow (MAF) Sensor faulty- Check Mass Air Flow (MAF) Sensor
Page 24
-59
EVAP canister purge regulator valve remains in
stuck in open position - Check EVAP canister purge
regulator valve Page 24
-134
Fuel pressure too highFuel return line kinked or pluged- Check fuel pressure regulator
Page 24
-33
- Check fuel return line
Fuel injector leaking- Check fuel injectors Page 24
-39
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Page 13 of 61
24-91
Evaluation display group 032 Display Group 32
Display fields: 1/3
Possible cause
Corrective action
Oxygen sensor adaptation
values in range:
4.0 and 25.0 %
Un-metered air in intake area- Check intake system for un-metered
air and eliminate leaks
Display field: 2/4
Fuel pressure too low- Check fuel pressure regulator Page
24
-33
Oxygen sensor adaptation
values in range:
4.0 - 25.0 %
Oxygen sensor heater faulty- Check oxygen sensor heater Page
24
-114
Injector not opening or only opening partially - Check injectors Page 24
-39
EVAP canister purge regulator valve remains
in stuck in open position - Check EVAP canister purge
regulator valve Page 24
-134
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Page 46 of 61
24-118
- Operate starter briefly.
Specified value: approx. battery voltage
If there is still no voltage reading:
- Check for open circuit and/or short circuit in
wiring between fuel pump relay and socket 1 on
the relevant oxygen sensor connector (on wiring
harness) via fuse.
Electrical Wiring Diagrams, Troubleshooting &
Component Locations If the voltage supply is OK:
- Connect hand-held multimeter (voltage measurement range) between
socket 2 (switched Ground (GND) connection from engine control
module) and B+ terminal using test leads from VAG1594 connector test
kit.
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