Checking Lambda probe ageing of Lambda probe 1 bank 1: VW (AQN, AXJ)
Step-by-step checking Lambda probe ageing of Lambda probe 1 bank 1 for the VW (AQN/AXJ): factory workshop text.
Workshop procedure for VW — the factory write-up, straight from real workshop data.
📐 47 workshop diagrams for AQN
Real factory drawings for this job — timing marks, bolt locations and routing. Locked in the free view.
📋 Procedure
The following description deals with the Golf 1998 ä, Bora 1999 ä. Therefore differences must be considered, if necessary.
Special tools, workshop equipment, testers, measuring instruments and auxiliary items required
V.A.G 1788/10 Engine speed adjuster
Fault reader V.A.G 1551 or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3
Test conditions
Coolant temperature must be at least 85 °C, =>display group 04, display zone 3.
Functional check
Connect fault reader V.A.G 1551 (V.A.G 1552). Start engine and select "Address word" 01 of engine control unit. When doing this the engine must be running at idling speed.
(Connecting fault reader and selecting engine control unit => Page
01-9
.)
Rapid data transfer
HELP
Select function XXX
Indicated on display:
Press keys 0 and 4 for the function "Introduction of basic setting" and confirm entry with Q key.
Basic setting
Input display group number XXX
Indicated on display:
Press keys 0, 3 and 4 for "Display group number 34" and confirm entry with Q key.
System in basic setting
34
⇒
1
2
3
4
Indicated on display:
(1...4 = Display zones)
Set an engine speed of 3000...3450 rpm with speed regulator V.A.G 1788/10:
Maintain engine speed until catalyst temperature in
display zone 2 rises to above 250 °C .
Check specifications in display zones 1...4.
If the diagnosis is initiated from engine control unit the display in display zone 4 jumps from "Test OFF" to "Test ON".
Continue to maintain the speed at 3000...3450 rpm until
the specification "B1-P1 OK" appears in
display zone 4.
If the specifications are not attained:
Carry out a road test to free Lambda probe of possible residues and repeat the test.
Observe the valid safety precautions when carrying out a road test => Page
24-33
.
If the specifications are again not attained:
Renew Lambda probe before catalyst (G39)
=>Page
24-1
, item
2
.
Interrogate fault memory, if necessary, repair any faults and then erase fault memory => Page
01-18
, interrogating and erasing fault memory.
Read-out the readiness code => Page
01-128
.
TorqFix answers live for your specific car — tell it the engine code and it serves the matching sequence, torque figures and wiring for that exact variant.
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Who makes these pages, and how
TorqFix was built by a mechanic — after a 2,700 km drive with five roadside repairs that no diagnostic tool could explain.
The figures on this page come from manufacturer workshop documentation and are shown as they are. The page is assembled automatically from that data — it is not written by an AI. The AI works in the chat, where it answers for your specific car. It writes nothing here.
Variants of the same model differ. Cross-check torque against the factory manual for your engine before final tightening.
Seen a figure that does not match your manual? Write to us — we correct it and note when. support@torqfix.com
The story behind TorqFix →Workshop data on this page last updated 20 Sep 2026.