Audi S3 EVAP Purge Valve Issues Causing Idle Stalls

As someone with moderate experience in automotive repair, I had a very similar issue with my 2013 S4 2.0T. The check engine light kept triggering, and I faced identical symptoms related to the EVAP system. After diagnosis, it turned out the issue was clogged hoses in the tank ventilation system. These hoses had accumulated debris over time, restricting proper vapour flow. The repair involved cleaning and replacing several components of the EVAP system. Total cost came to 175 Euro including parts and labor. The symptoms you describe, especially the stalling at idle, match what I experienced. The engine runs smoother at higher RPMs because the increased vacuum helps overcome the restriction in the system. To help diagnose your specific case more accurately, could you share: Have you scanned for specific error codes? Does the problem get worse after refueling? How long has the check engine light been appearing? Any recent fuel system maintenance performed? These details would help determine if your S3 is facing the same EVAP system issue I encountered.

Last service was at 45000 KM and I had the codes scanned. Got P0441 and P0442 errors related to the EVAP system. The check engine light started appearing more frequently after refueling, especially when the gas cap wasnt tight enough. The pressure sensor readings were inconsistent according to the diagnostic scan. I cleaned the gas cap seal but the problem persists. Would testing the purge valve be the next logical step? Want to avoid replacing parts out of nowhere.

Thanks for providing those diagnostic codes and additional details, they match exactly what I experienced with my S3 before resolving the issue. The P0441/P0442 codes plus symptoms worsening after refueling strongly indicate an EVAP system leak, but the gas cap isnt always the culprit. In my case, even after cleaning and replacing the gas cap seal, the check engine light persisted. Testing the purge valve is definitely the next logical step. When my purge valve failed, it caused similar pressure sensor inconsistencies. The test is relatively straightforward using a multimeter to check the solenoid resistance. Here is what worked for my car: 1. Tested purge valve, found it wasnt closing properly 2. Replaced purge valve (85 Euro for the part) 3. Inspected all EVAP hoses for cracks while system was exposed 4. Cleared codes and monitored for recurring issues The unstable idle completely resolved after replacing the faulty purge valve. The entire fuel tank pressure system started working correctly, and the check engine light hasnt returned in over 8 months. Before replacing any parts, have the purge valve tested to confirm its the source of your EVAP system problems. This approach saved me from unnecessary parts replacement.

Thanks for the detailed feedback about the EVAP system issues. Those P0441 and P0442 codes combined with the refueling symptoms make a lot of sense. I will definitely get the purge valve tested before replacing any parts. Good point about checking the hoses while the system is exposed, might as well inspect everything in that area. The unstable idle is really annoying, especially since the car runs fine otherwise. Will schedule a diagnostic test focusing on the purge valve and tank ventilation components. 85 Euro for a new valve sounds reasonable if that ends up being the problem. My pressure sensor readings match what you experienced, so I am hopeful this targeted approach will resolve the check engine light and idling issues. Thanks for walking through your repair experience, really helpful to know what fixed a similar EVAP system problem. Will update once I get the purge valve tested and hopefully solve these recurring symptoms.