2000 AUDI A4 heating

Oxygen sensor control can basically be evaluated both in "Basic Setting" function 04 as well as in "Read Measuring Value
Block" function 08 only after successful learning ( learning requirement display). Oxygen sensor control shows momentary control status. After successful learning, ( learning requirement display),
values vary around 0.0 6.0%. If the learning process (display field 4) is ended and no value around 0.0 6.0% is
obtained, observe display group 010, display fields 3 and/or 4 and check control behavior of the two heated oxygen
sensors. During this process, the display values must at times drop below 0.3 V and exceed 0.6 V, otherwise check
oxygen sensor heating and the heated oxygen sensor.
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01-207
Note on display field 3: X
X
Meaning of the 2-digit display:

1 = A/C compressor off/on (0 = off; 1 = on)
Notes:

On vehicles without A/C "0" is always displayed.
Check A/C compressor page 24
-90
.
The A/C compressor is shut off for approx. 12 sec. by -J192- when accelerating from a stop and from low speed.
If the gas pedal is released sooner, the time is reduced to a minimum of 3 sec. At wide open throttle, the A/C
compressor is switched off by the automatic transmission (kick-down switch).

2 = Rear window heating - Signal (0 = off; 1 = on)
Notes:
The rear window heating signal is only displayed on vehicles without A/C.
On vehicles with A/C "0" is always displayed.
Check rear window heater signal page 24
-88
.
Notes on display field 4:

If the A/C compressor is off display field 3; display field 4 can be used to recognize whether the compressor was
switched off by the engine control module. Meaning of the 1-digit display:
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01-212
If the trip status display is set to "1" when the readiness code is regenerated, but the corresponding display value of the
readiness code is not set to "0", the diagnosis was carried out but recognized as not OK by the engine control module. In this
case, the DTC memory should be checked to determine malfunctions and/or to carry out a selective diagnosis:

For three way catalytic converter diagnosis (Bank 1 and 2) also check display groups 035, 036 and 044.
For the Evaporative Emissions (EVAP) system leak diagnosis, also check display group 030.
For the Secondary Air Injection (AIR) system throughput and leak diagnosis, also check display groups 020 and 021.
For oxygen sensor diagnosis, also check display groups 032, 033, 034, 041, 042 and 043.
For oxygen sensor heating diagnosis, also check display group 040.
For the Exhaust Gas Recirculation (EGR) system throughput diagnosis, also check display group 017.
Display
shows Display specified
value Designation/diagnosis
Basic setting
29
1 2 3 4 X X X X X X 1 = Readiness Code
X X X X X X X X 2 = Trip Status display
0 - 40 3 = Counter for warm-up phases without new malfunctions except for "combustion
misfiring" and/or "oxygen sensor control"
0 - 40 4 = Counter for warm-up phases without new malfunctions except for "combustion
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01-213
Notes on display field 1:

All readiness code values are set to "1" by disconnecting the ECM harness connector and/or disconnecting the battery,
and every time DTC memory is erased (both with address word 01 function 05 and with address word 33 mode 4).
To regenerate the readiness code, take 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 ("mixed city
and highway" trip).
Value "0" = Diagnosis carried out
Value "1" = Diagnosis not OK and/or diagnosis not carried out yet
X
X
X

X
X

X
Meaning of the 6-digit "readiness codes"

1 = Three way catalytic converter diagnosis (Banks 1 and 2)

2 = ----

3 = Evaporative Emissions (EVAP) throughput diagnosis

4 = Secondary air system throughput and leak diagnosis (Always "0" for vehicles without
secondary air injection system)

5 = ----

6 = Heated oxygen sensor diagnosis (flank rise and/or flank fall time of the voltage signal of
heated oxygen sensors in front of three way catalytic converters

7 = Oxygen sensor heating diagnosis (all four O2S heaters)

8 = Exhaust Gas Recirculation (EGR) throughput diagnosis
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(for diagnostic conditions display groups 007 and 008)

6 = Heated oxygen sensor diagnosis (flank rise and/or flank fall time of the voltage signal on
the heated oxygen sensor in front of three way catalytic converter; for diagnostic conditions
display group 042)
7 = Oxygen sensor heating diagnosis (all four O2S heaters)

8 = Exhaust Gas Recirculation (EGR) system throughput diagnosis
(for diagnostic conditions display group 017)
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01-231
Display group 040 (Heating current of oxygen sensors in front of and behind three way catalytic converter) Display
shows Display specified value
Designation/diagnosis
Basic setting
40
1 2 3 4 At cold start, greater than 3 A after approx. 40 sec: 0.7 -
1.0 A 1 = Heating current, bank 1, heated oxygen
sensor 1
2 = Heating current, bank 2, heated oxygen
sensor 1
At cold start, greater than 3 A after approx. 80 sec: 1.2 -
1.4 A 3 = Heating current, bank 1, heated oxygen
sensor 2
4 = Heating current, bank 2, heated oxygen
sensor 2 Notes:

The current values specified apply only at when battery positive voltage (B+) is 12-14 volts display group 001, display
field 4. The heating of the heated oxygen sensors in front of the three way catalytic converter is switched on with the fuel pump
relay, i.e. immediately at engine start.
The heating of the heated oxygen sensors behind the three way catalytic converter is not switched on immediately at
engine start, but only when the calculated exhaust gas temperature in the three way catalytic converter exceeds 308 C
(586 F) display group 044, display field 2. In order to reach an exhaust gas temperature of 308 C (586 F) in the three
way catalytic converter after a cold start, the car must be driven about 20 sec. with an increased engine speed of 2500
RPM.
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01-232
Display group 041 (Voltage signal of oxygen sensors in front of and behind three way catalytic converter) Display
shows Display specified
value Designation/diagnosis
Basic setting
41
1 2 3 4 _.___ V 1 = Voltage signal, bank 1, heated oxygen sensor 1 display group 010, display
field 3 _.___ V 2 = Voltage signal, bank 2, heated oxygen sensor 1 display group 010, display
field 4 _.___ V 3 = Voltage signal, bank 1, heated oxygen sensor 2
_.___ V 4 = Voltage signal, bank 2, heated oxygen sensor 2 Notes on display field 3 and 4:

The voltage signals of bank 1 heated oxygen sensor 2 and/or bank 2 heated oxygen sensor 2 should not be evaluated
until at least 50 sec. after the oxygen sensor heating is switched on display group 040. With cold engine and ignition on, a voltage signal of 0.400 volts is displayed in all four display fields. With very hot engine
and ignition on, a signal of 0.000 volts is displayed in display field 3 and 4.
The voltage signal of the heated oxygen sensors behind the three way catalytic converter must lie between about 0.5 volts
and 0.6 volts with a three way catalytic converter with sufficient effect (conversion). During deceleration fuel shut off, the
voltage signal must be less than 0.1 volts constantly. During operation with wide open throttle enrichment, the voltage
signal must be greater than 0.6 volts.
If there is wide open throttle (signal voltage during wide open throttle enrichment greater than 0.6 volts) with a new three
way catalytic converter, distance driven less than 5,000 km (3,000 mi.) after a preceding deceleration fuel shut off (signal
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01-236

X
X
X
X
X
X
X
X
Meaning of 8-digit "Diagnosis condition 2"

1 = Constant drive

2 = Oxygen sensor heating, bank 1 OK ( display group 040)
3 = Oxygen sensor heating, bank 2 OK ( display group 040)
4 = Vehicle speed: 80 - 100 km/h (50 to 63 mph) ( display group 003)
5 = Value does not drop below or exceed oxygen sensor control limit for bank 2 ( display
group 008)
6 = Value does not drop below or exceed oxygen sensor control limit for bank 1 ( display
group 007)

7 = Calculated exhaust gas temperature in front of three way catalytic converter: 400 - 640 C
(752 - 1184 F)
8 = Throttle angle constant ( display group 003) Re: 5 and 6: With a lot of fuel vapor on the EVAP system diagnosis, use function 04 to carry out "Basic Setting" (EVAP
system automatically shut off during function 04).
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