Audi RS3 Stalling Issue Linked to Purge Valve Failure

Had similar symptoms with my 2018 Audi S4. The check engine light and stalling pointed to EVAP system issues. The emission system pressure sensor was reporting incorrect readings due to clogged ventilation hoses between the fuel tank and purge valve. Initial diagnosis showed the purge valve was functioning, but debris had accumulated in the hoses over time, restricting proper fuel tank ventilation. The clog was preventing normal pressure regulation, causing the stalling during idle. This was a serious issue requiring complete EVAP system inspection. The repair involved cleaning the entire ventilation pathway and replacing two damaged hoses that had deteriorated. The check engine light cleared after repair and the stalling never returned. Not a simple gas cap issue in my case, the symptoms match a blocked EVAP system that needs proper diagnosis. Would recommend getting the pressure sensor readings checked first to confirm if its the ventilation system before replacing parts.

Thanks for sharing your experience with the EVAP system problems. My ventilation hose issues and faulty pressure sensor turned out to be a bigger repair than expected too. Been about 8 months since I got it fixed and thankfully no check engine lights or stalling since then. Just curious, do you remember roughly what the automotive repair ended up costing you? My fuel tank ventilation work was pretty expensive but sounds like you had more components needing attention. Also wondering if youve had any other related issues pop up since the fix?

Just had my mechanic confirm last week that the tank ventilation valve malfunction was completely resolved. The repair bill came to 175 Euro for cleaning and replacing the clogged hoses in the EVAP system. Honestly, it was worth every cent since the check engine light hasnt returned and the engine runs smoothly at idle now. The purge valve itself was actually working fine, just like in your case. The main culprit was debris buildup restricting proper ventilation flow. Since the fix, the emission system has been functioning perfectly with no related issues whatsoever. If anyone else encounters similar symptoms, getting the EVAP system properly diagnosed is crucial. What seems like a simple gas cap issue can often be more complex when dealing with fuel tank ventilation problems.

Thanks for your detailed response about the repair costs. After dealing with this headache, I finally took it to a different automotive repair shop that actually knew what they were doing. The mechanic found both a clogged ventilation hose and a faulty emission system pressure sensor. Total repair came to 450 Euro which included replacing the hoses, sensor, and complete system cleaning. The first shop had just cleared the check engine light without fixing the underlying tank ventilation issue. Glad I got a proper diagnosis the second time around. Now 8 months later, no more stalling or warning lights. Really pays to find a mechanic who takes time to properly troubleshoot these EVAP system problems instead of just guessing.