Testing intake manifold changeover valve — AUDI
Testing intake manifold changeover valve on Audi: factory workshop procedure for engines ADR, AEH, AFY, AHK. Full factory text, tools and checks.
Workshop procedure for AUDI — the factory write-up, straight from real workshop data.
📋 Procedure
AFY
Electrical test of intake manifold changeover valve -N156
Fitting location =>Page
24-4
.
Unplug connector from intake manifold changeover valve -N156.
Measure resistance between the injector contacts using V.A.G 1526.
Specification: 25...35 Ohms
If the reading does not match the specification, renew intake manifold changeover valve -N156.
Testing power supply to intake manifold changeover valve -N156
Remove connector from valve for intake manifold changeover function -N156.
Connect diode test lamp V.A.G 1527 between engine earth and contact 1 (positive) on connector using cables from adapter set V.A.G 1594.
Operate the starter briefly.
The diode test lamp should light up.
If the diode test lamp does not light up, carry out the following tests:
Test fuse for -N156.
Test for open circuit in wiring between fuse and contact 1 on connector for intake manifold changeover valve using current flow diagram.
=> "Current Flow Diagrams, Electrical Fault Finding and Fitting Locations" binder
Specification: max. 1 ω.
Check the fuel pump relay and actuation => Page
24-29
.
Testing activation of intake manifold changeover valve
Connect diode test lamp V.A.G 1527 between contacts 1 and 2 on connector for intake manifold changeover valve using cables from adapter set V.A.G 1594.
Start the final control diagnosis => Page
01-44
. The diode test lamp should flash when the intake manifold changeover valve is being activated.
If the diode test lamp does not flash or lights up continuously, connect test box V.A.G 1598/22 to wiring harness for engine control unit
=> Page
24-6
.
If the diode test lamp lights up continuously, test for short to earth in wiring between contact 2 on connector for intake manifold changeover valve and socket 64 on V.A.G 1598/22 test box.
If the diode test lamp does not flash, test for open circuits and short circuits to positive in the wiring between contact 2 on ACF valve connector and socket 64 on test box.
Specification: max. 1 ω.
Rectify the short-circuit or open-circuit as appropriate.
If no open circuits or short circuits are found, fit a new engine control unit =>Page
24-7
.
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.