Audi S3 Stalls: EVAP System Causing Idle Issues

Had similar issues on a 2012 Audi S4 with stalling and check engine warnings. The main problem turned out to be a defective activated charcoal filter in the EVAP system. The symptoms perfectly match what you describe, unstable idle and incorrect pressure readings. The EVAP system failure caused fuel vapors to build up incorrectly, leading to emission control problems and engine performance issues. The repair involved replacing the complete charcoal canister assembly and purge valve. This is a critical repair that should not be postponed, as it affects both fuel efficiency and emissions compliance. The job requires accessing components near the fuel tank, but its not overly complex for an experienced mechanic. The important part is using OEM parts for the EVAP components to ensure proper system function. After replacement, the system needed proper initialization with a diagnostic tool to reset the fuel vapor management. The repair resolved all issues, no more stalling, normal pressure readings, and check engine light cleared permanently. This is a known weak point on this engine family, but once fixed properly it typically doesnt recur.

Thanks for sharing your experience. This sounds exactly like what I am dealing with right now, including the pressure sensor inconsistencies and fuel tank ventilation issues. Great to hear it was fixable with the charcoal canister replacement. Could you share roughly what the total repair cost was? Also wondering if youve had any emission control related problems since getting it fixed? Just want to make sure I budget properly and know what to expect long term regarding fuel efficiency and system reliability.

Just had this fixed last week actually. Total cost was 275 Euro for the complete repair including the new activated charcoal filter and labor. This resolved the fuel tank ventilation system leak completely, money well spent considering the problems it was causing. No emission control issues since the repair. Fuel efficiency has actually improved a bit now that the system is working properly. The check engine light hasnt come back and pressure sensor readings are steady. The idle is smooth again too, which makes a huge difference in daily driving. For long term reliability, these EVAP system repairs typically last when done with quality parts. Its been a solid fix and the system failure symptoms havent returned at all. Just make sure your mechanic uses proper OEM components for the repair to avoid future issues.

I took your advice and got it fixed last week. Found a mechanic who specializes in leak detection and EVAP systems. The whole repair including parts and labor came to 290 Euro, which was better than expected. The fix involved replacing the charcoal canister and cleaning the entire emission control system. They showed me the old parts, the canister was completely shot, explaining the pressure sensor problems. After the repair, the check engine light cleared right away and the engine runs perfectly at idle. Best part is the fuel efficiency has improved noticeably. No more stalling issues and the pressure readings are now stable. Wish I had done this repair sooner instead of worrying about getting overcharged. The mechanic was straight forward about the problem and the fix worked exactly as described.