Testing Lambda probe -G39 and Lambda control — AUDI

ADW
Note:

A fault relating to the function of the lambda control system can only be checked after a test drive of at least 5 minutes duration (time-related fault detection).

Special tools, testers and auxiliary equipment required

Hand-held multimeter V.A.G 1526 or V.A.G 1526 A
Fault reader V.A.G 1551 (or vehicle system tester V.A.G 1552) with wire V.A.G 1551/1
Adapter set V.A.G 1594 A
Test box V.A.G 1598/18

Test requirements:

No leak in exhaust system between catalytic converter and cylinder head.
Lambda probe heater OK; testing => Page
24-76
.

Connect fault reader V.A.G 1551 (V.A.G 1552) and select the engine electronics control unit using "Address word" 01. The engine must be running at idle speed
(Connect fault reader and select engine electronics control unit => Page
01-2
.)
Read measurement block 1
⇒
1
2
3
4
Read measured value block, display group 001 => Page
01-57
.
Do not proceed with the test until the following conditions are met:
Readout in display zone 2 greater than 80 oC
Readout in display zone 4.
5. position = 0 (lambda control)
8. position = 0 (coolant temperature)

Read off the figure in display zone 3
Specification: varies between 0.1 and 1.1 V

If the lambda probe voltage fluctuates very slowly, test the lambda probe heating => Page
24-76
.
If the display shows a constant lambda probe voltage reading of 0.45 - 0.50 V, this means there is an open circuit in the signal wiring, check the wiring => Page
24-74
.
Press the ⇒key.

Rapid data transfer
HELP
Select function XX
Indicated on display:

Enter "06" for "End output" function and confirm entry with Q key.

If the specification is not obtained:

Test lambda probe => Page
24-75

Testing wiring

Set hand-held multimeter V.A.G 1526 to voltage measuring range (2 V direct current) and connect it to the connector on the engine control unit and engine earth using test leads from V.A.G 1594 A.
Switch the ignition on.
Specification: 450 ± 50 mV.

If the specification is not obtained:

With the ignition switched off, connect test box V.A.G 1598/18 to connector for engine control unit => Page
24-16
.
Test the wiring connection of the lambda probe -G39 to socket 17 of test box V.A.G 1598/18 for an open circuit.
Rectify open circuit, if necessary

Testing Lambda probe

Switch off ignition.
Separate the plug connection for the signal wire of the lambda probe => -Pos.
24-6
.
Set hand held multimeter V.A.G 1526 to the resistance measuring range and connect it to the lambda probe and engine earth using the auxiliary leads from V.A.G 1594 A.
Specified value: ∞ω

If the specification is not obtained:

Fit a new Lambda probe.