sensor AUDI A6 1996 C5 / 2.G AHA Engine Multiport Fuel Injection And Ignition System Service Manual

24-63

Oxygen Sensor (O2S) aging, bank 2,
sensor 1, checking


Required special tools and test equipment

VAG1551 or VAG1552 Scan Tool (ST) with
VAG1551/3 adapter cable

Test requirements
Engine Coolant Temperature (ECT) at least
80 C (176 F)

Function test

- Connect VAG1551 or VAG1552 scan tool and
press buttons -0- and -1- to insert "Engine
Electronics" address word 01 (with engine
running at idle) page 01
-8 .
Rapid data transfer
HELP
Select function XX

Indicated on display
- Press buttons -0- and -4- to select "Basic Setting" function 04, and
press -Q- button to confirm input.
System in Basic Settin
g
HELP
Input display group number XXX

Indicated on display
- Press buttons -0-, -3- and -5- to input display group number 35 (035),
and press -Q- button to confirm input.
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24-64

- Increase engine speed to 1800-2200 RPM.

- Maintain engine speed at 1800-2200 RPM until
display field 4 changes from "Test OFF" to "Test
ON."

- Maintain engine speed at 1800-2200 RPM and
compare display with specified values for
oxygen sensor aging (before TWC) in display
fields 3 and 4).

Note:
To be sure that the temperature is within the
specified range, the specified RPM has to be
maintained for at least 1 minute.

Display fields

1 2 3 4
Display group 35: Oxygen sensor aging (time period check of oxygen sensor) bank 2, sensor 1
Display xxxx RPM xx.xx ms xx.xx s Test OFF/Test ON
B2-S1 OK/B2-S1 n.OK
Indicates Engine speed
(in 40 RPM steps) Engine load Time period
Bank 2, Sensor 1 Diagnostic status
Diagnostic result
Range 0 - 6800 RPM 0.00 - 12.75 ms --- ---
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24-65

Continuation
If displayed value is NOT OK (not as specified):

- Road test to condition oxygen sensor (eliminate
possible contamination) and repeat test.
If displayed value is still NOT OK:

- Replace HO2S -G108-.

- Check readiness code page 01
-70
. If
Diagnostic Trouble Code (DTC) memory has
been erased, or ECM was disconnected,
generate new readiness code page 01
-73
.
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24-68

Mass Air Flow (MAF) sensor, checking


Required special tools and test equipment

VAG1551 or VAG1552 Scan Tool (ST) with
VAG1551/3 adapter cable
VAG1598/22 test box
Multimeter US1119 (Fluke 83 or equivalent)
VW1594 connector test kit
Wiring diagram

Test requirements
All electrical consumers switched off (coolant
fan must not run during test).
A/C must be switched off
Fuse for MAF sensor OK
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24-72
Evaluation of display group 2, display field 4 Display
group: 2


Display field:
4
Possible malfunction cause
Corrective action
less than 2.8
g/s
Large amount of false air between intake air duct and
Mass Air Flow (MAF) sensor - Check intake air system for leaks (false
air) page 24
-126

larger than 5.6
g/s
Shift lever in drive range (auto. transmission)
Engine affected by additional consumers- Move shift lever into P or N
- Eliminate load (A/C, power steering,
generator)

Open circuits in wire 1 or 2 between MAF sensor and
ECM - Check voltage supply page 24
-73


Open circuit in wire 3 between MAF sensor and relay
panel - Check wiring page 24
-73
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24-73

Checking voltage supply

If there is no voltage:
Checking wiring - Disconnect 3-pin harness connector from Mass Air Flow sensor (MAF).
- Connect multimeter US1119 (Fluke 83 or equivalent) between harness
connector terminals 2 (Ground) and 3 (B+), using adapter cables from
VW1594 connector test kit.
Specified value: 9.0-14.5 volts
- Switch ignition off.
- Check wiring using applicable wiring diagram.
- Switch ignition off.
- Connect VAG1598/22 test box to ECM harness connector page 01
-
67
.
- Check wiring for open circuits, between ECM/test box and 3-pin MAF
sensor harness connector.

Connector terminal 1 to ECM/test box socket 13
Connector terminal 2 to ECM/test box socket 12
Specified value: max. 1.5
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24-74

- Check wiring for short circuits between terminals
of 3-pin connector, and between connector and
ECM/test box.


Connector terminal 1 to ECM/test box
socket 12

Specified value:

- Switch multimeter to 20 VDC measuring
range.

- Check wiring at 3-pin connector for short circuit
to B+ (battery positive voltage), according to
applicable wiring diagram.


Connector terminal 1 to vehicle Ground

Connector terminal 2 to vehicle Ground

Specified value: 0 volts
If wiring is OK:

- Replace Mass Air Flow sensor (MAF) -G70-.

-
Check readiness code page 01
-70
. If
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24-75

Engine Coolant Temperature (ECT)
sensor, checking


Required special tools and test equipment

VAG1551 or VAG1552 Scan Tool (ST) with
VAG1551/3 adapter cable
VAG1598/22 test box
Multimeter US1119 (Fluke 83 or equivalent)
VW1594 connector test kit
Wiring diagram

Test requirements
Engine cold
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24-77

- Compare display with specified value for engine
coolant temperature sensor (display field 3):

Display fields

1 2 3 4
Display group 4: General engine data
Display xxx RPM xx.xxx V
xxx.x C
xxx.x C
Indicates Engine
speed
(in 40 RPM
steps) Battery Positive
Voltage (B+) Engine coolant temperature Intake air
temperature
Range 0 - 6800
RPM 0.000 - 16.500 V -46.5 to 141.0 -46.5 to 141.0
Specified
value 0 RPM 10.000 - 14.500 V approx. ambient temperature 1), 2) ---

--- --- If specified value is not attained page 24
-79
,
Evaluation of display group 4
---
1) After a long standing period (approx. 12 hours). 2) If indicated temperature deviates significantly from the ambient temperature, check ECT sensor wiring for resistance or
open circuits.
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24-78

Continuation

- Start engine and let run at idle.

Temperature value must increase evenly
If NOT:

-
Press button.

- Press buttons -0- and -6- to select "End Output"
function 06, and press -Q- button to confirm
input.

- Switch ignition off.

- Replace Engine Coolant Temperature (ECT)
sensor -G62-.

Notes:

Temperature is displayed in increments of 1.5
C.

If malfunctions occur within certain temperature
ranges while the engine is running, and the
temperature values do not increase without
interruption, the temperature signal is
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