Audi A1 Engine Stalling Issues Point to Vacuum Leak

Having worked on my A3 from around the same time period with similar symptoms, this sounds very familiar. As someone with moderate car repair experience, I can share what worked in my case. The main issue was a faulty vacuum hose connection between the pump and valve. The check engine light was constantly on and the engine struggled with maintaining steady power, particularly during low-speed driving. After checking the air supply system, the workshop discovered that the throttle body was getting inconsistent readings due to a vacuum leak. The repair involved replacing the defective hose connection, which cost 175 Euro including labor. After the fix, the engine performance returned to normal and the check engine light cleared up. To help diagnose your case more precisely, could you share: Build year of your A1, Engine size, When did these symptoms first appear, Have you noticed any unusual sounds from the engine bay, Does the problem get worse when the engine is warm or cold These details would help determine if your issue matches what I experienced with my A3.

Thanks for the detailed response. My A1 actually had 2 services since I noticed the issues at 165343 KM. The mechanic found a significant vacuum leak near the air intake manifold, causing idle problems and triggering the check engine light. Although the symptoms matched your experience, the air valve assembly also needed replacement. The total repair came to 320 Euro. The engine now maintains steady power and all warning lights have cleared.

Glad to hear you got it fixed. My A3 also needed the air valve assembly replaced about 10000km after the initial vacuum leak repair I mentioned. The symptoms were nearly identical, check engine light and idle problems. These components often wear out around similar mileage points. The repair cost you mentioned is in line with what I paid for the full fix. The throttle body and air intake system on these models need careful attention, especially after 150000km. Regular cleaning of the air intake components helps prevent these issues from recurring. Make sure to monitor for any changes in engine performance. If you notice the idle problems starting to return, getting the throttle body cleaned might help prevent another full repair. The newer air valve assemblies seem more durable than the original parts. Mine has been running strong for 40000km since the replacement with no check engine warnings or performance issues.

Thanks everyone who replied. The issue is now completely resolved. After the vacuum leak fix and air valve assembly replacement, my A1 runs perfectly again. The idle problems and check engine warnings are gone, and power delivery is smooth at all speeds. The 320 Euro repair cost was worth it since the car feels like new. Regular throttle body maintenance is now on my checklist to prevent similar issues. Thanks again for helping me understand what caused the problems and confirming the repair costs were reasonable.