Checking the altitude sensor: Audi 1.8 (AEB, AJL)
Step-by-step checking the altitude sensor for the Audi 1.8 (AEB/AJL): factory workshop text. What to remove, in what order, and what to check after.
Workshop procedure for AUDI — the factory write-up, straight from real workshop data.
📐 46 workshop diagrams for AEB
Real factory drawings for this job — timing marks, bolt locations and routing. Locked in the free view.
📋 Procedure
AJL
The altitude sensor signal influences:
The boost pressure control
The boost pressure control prevents the turbocharger from over revving when the altitude increases and consequently the air density decreases.
A decrease in air density (lower air pressure) causes the turbocharger to increase its charging rate (higher speed) to produce the required boost pressure.
This results in a higher charge air temperature and an increased risk of engine knock. To avoid this, the boost pressure is limited.
Composition of mixture when starting the engine
The richness of the starting mixture is determined by mapped characteristics stored in the engine control unit and is leaned out according to a correction factor determined by the altitude sensor as the altitude increases (lower air density as the air pressure decreases).
Switch the ignition on.
Select the function "Read measured value block" (function 08) and Display Group 18 =>Page
01-103
.
Read measurement block 18
⇒
1
2
3
4
Display readout:
Observe display zone 4.
Display in / Display zone 4 · Air pressure / in mbar
0 % · 1013 mbar / (sea level)
-10 % · 900 mbar / (altitude 1.000 m)
-20 % · 800 mbar / (altitude 2.000 m)
-30 % · 700 mbar / (altitude 3.000 m)
If an implausible value appears in display zone 4:
Pull off the connector on the sensor => Overview of fitting locations, Page
24-5
.
Switch the ignition on.
Connect the V.A.G 1526 hand held multimeter for voltage measurement between the following connector contacts:
3-pin connector on the wiring harness contact. · Specification
1 + 3 · approx. 5 V
2 + 3 · approx. 5 V
If the specified values are not obtained:
Switch off ignition.
Connect test box V.A.G 1598/22 to wiring harness for engine control unit =>Page
24-7
The following wiring connections are to be examined for open circuits and/or short to positive or negative.
3-pin connector on the wiring harness contact. · Test box V.A.G 1598/22 contact
1 · 61
2 · 62
3 · 67
Rectify short circuit or open circuit if necessary.
If no wiring fault is detected:
Replace the altitude sensor (F96).
If an implausible value is still displayed after the replacement of the altitude sensor, replace the engine control unit => Page
24-9
.
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.
Ask about my car →Other AUDI procedures
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- Testing fuel pump relay
- Checking the solenoid valve for boost pressure control
- Perform adaptation of the throttle valve control unit
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- Removing and installing camshaft timing chain · 29 torque figures
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.