Checking exhaust gas recirculation - Vehicles up to 07.99 — AUDI
Checking exhaust gas recirculation - Vehicles up to 07.99 on Audi: factory workshop procedure for engines AGR, AHF, ALH, ASV.
Workshop procedure for AUDI — the factory write-up, straight from real workshop data.
📐 34 workshop diagrams for AGR
Real factory drawings for this job — timing marks, bolt locations and routing. Locked in the free view.
📋 Procedure
AHF ALH ASV
The operation of the exhaust gas recirculation system is tested by measuring the intake air mass. If the exhaust gas is being recirculated the proportion of fresh air detected by the air mass meter is lower. The larger the quantity of recirculated exhaust gas, the lower the signal from the air mass meter.
Special tools and workshop equipment required
VAS 5051 with VAS 5051/1
Test requirements:
Vehicle diagnostic, testing and information system VAS 5051 connected, vehicle self-diagnosis and vehicle system "01 - Engine electronics" selected.
Engine running at idling speed
Coolant temperature at least 80 °C=> display group 001, display zone 4.
Final control diagnosis has been performed
Test sequence
Display on VAS 5051:
Under -1- select the diagnostic function "08 - Read measured value block".
Display on VAS 5051:
1 -
Enter display group
max. input value = 255
Enter "003" for "display group number 003" in zone -2- and confirm the entry by pressing the Q button.
Briefly depress the accelerator pedal, then allow the engine to continue running at idling speed.
Display zones
1 · 2 · 3 · 4
Display group 003: Exhaust gas recirculation at idle
Display · xxxx rpm · xxx mg/stroke · xxx mg/stroke · xx %
Display · Engine speed · Air mass (specified) · Air mass (actual) · Checking actuation of EGR valve -N18
Specified value · 860...940 rpm · 230...370 mg/stroke · 210...390 mg/stroke · 30...80 %
Note: · If a value higher than 370 mg/stroke is displayed: Engine too cold => run until warm · If specified value is not attained: Evaluation => Page 26-27
Evaluation of display group 003
Display zone: 3 · Possible causes of fault · Fault remedy
Constant · - Open circuit in wiring to air mass meter · - Testing air mass meter
425 mg/stroke · - Air mass measured not plausible · => Diesel Direct Injection and Glow Plug System (4-cyl TDI) > 07.99; Repair group 23 / => TDI-Injection- and Glow Plug System(4-cyl.) 08.99 >; Repair group 23 TDI-Injection- and Glow Plug System(4-cyl.) 08.99 >
Over · - Engine has been running for 10 min at idling speed · - Briefly depress accelerator sharply
390 mg/stroke · - Excessive exhaust gas recirculation · - Checking mechanical exhaust gas recirculation valve => Page 26-33
- Engine load from ancillaries · - Eliminate load (AC system/power steering/alternator)
- Intake manifold temperature too high
- Injection pump too lean · => Diesel Direct Injection and Glow Plug System (4-cyl TDI) > 07.99; Repair group 01 / => TDI-Injection- and Glow Plug System(4-cyl.) 08.99 >; Repair group 23 TDI-Injection- and Glow Plug System(4-cyl.) 08.99 >
Less than · - Unmetered air in intake area · - Check intake are for leaks
210 mg/stroke · - Excessive exhaust gas recirculation · - Checking mechanical exhaust gas recirculation valve => Page 26-33
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.