display AUDI A4 1995 B5 / 1.G AWM Engine Oxygen Sensor Control Checking Owner's Manual

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Display fields

1 2 3 4
Display group 037: Diagnostic oxygen sensor control system
Display xxx %
x.xxx V
x.xx
---
Indicated Engine
load Oxygen sensor voltage
Bank 2, sensor 1 Oxygen sensor correction value
between bank 1, sensor 1 and
bank 1, sensor 2 Diagnostic condition
Functional
range


Test OFF
Test ON
System OK
System not OK
Specified
value 13 to 40
% 0.100 to 0.950 volts
smaller than 0.02 System OK
Note

If specified value is not
obtained: Evaluation
Page 24
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If "System not OK" is
displayed: Check DTC
memory Page 01
-12

Note for display field 2:
Oxygen sensor voltage bank 1, sensor 2 should remain fairly constant. Strong voltage fluctuations point to a damaged
catalytic converter.
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Evaluation display group 037 Display field: 2
Possible cause
Corrective action
constant about
0.450 V
Open circuit in wire 4 between oxygen sensor
and control module - Check primary voltage Page 24
-104


Open circuit in wire 3 between oxygen sensor
and control module
larger than
0.950 V Short circuit to B+ in wire 4 between oxygen
sensor and control module - Check oxygen sensor wiring, oxygen sensor after
catalytic converter Page 24
-105

smaller than
0.100 V
Short circuit to Ground (GND) in wire 4 between
oxygen sensor and control module
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Continuation
If specified value in display field 3 and 4 is not
obtained:

- Road test vehicle in order to free oxygen sensor
of possible residue and repeat test.
If specified value in display field 3 and 4 is not
obtained, even after road test:

- Replace Heated Oxygen Sensor (HO2S) -
G39-.

Note:
If oxygen sensor voltage is OK and oxygen
sensor correction value is still above 0.02 ms,
even after a road test, this suggests aging of an
oxygen sensor before catalytic converter.
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24-109
If specified value is obtained:

- Check voltage supply of oxygen sensor
heating.

Checking voltage supply for oxygen sensor
heating

Note:
When the Engine Control Module (ECM) switches oxygen sensor heating
on and off, it may be observed via the function "read measuring value
block", in display group number 041 display field 4.
If there is no voltage: - Connect multimeter between terminal 1 (B+) and 2 (Ground -GND-) for
voltage measurement.
- Start engine.

Specification: approx. battery voltage

- Connect multimeter for voltage measurement as follows:Harness connector
Terminal
Measure to
1 (B+) Vehicle Ground (GND)
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