Audi Q5 Stalling: Hidden Fuel System Leak Alert

This sounds very familiar. Had similar issues with my 2014 Audi Q3 2.0T last year. As someone with some hands-on experience working on VAG engines, I can share what worked in my case. The symptoms match exactly what I experienced, check engine light and rough idling. After initial diagnosis, my issue was traced to a faulty activated charcoal filter in the EVAP system. The defective filter was causing incorrect fuel tank pressure readings and affecting the entire emission control system. The repair involved: Complete EVAP system diagnostic, Replacement of activated charcoal filter, System pressure test, ECU reset Total cost was 275 Euro and resolved both the check engine light and idle issues. Fuel efficiency improved noticeably after the fix. Before suggesting more specific solutions, could you share: Any fuel smell around the vehicle? Does the problem get worse after refueling? Have you noticed any decrease in fuel efficiency? Any specific error codes from the check engine light? This information would help determine if your issue is identical to what I encountered with the EVAP system.

Last service was at 149000 KM, and currently at 153191 KM. The air flow readings have been inconsistent, and I now notice a strong fuel smell after these symptoms started. The engine stalls mostly after refueling, which seems to confirm the fuel tank ventilation issue mentioned earlier. Running a diagnostic showed error code P0456, pointing to a small EVAP leak. A new purge valve might be the solution, but I wanted to verify with the community before proceeding with repairs.

Thanks for the additional details, those symptoms match my experience exactly. The P0456 code plus the fuel smell and post-refueling stalls are classic signs of an EVAP system problem. On my Q3, replacing just the purge valve didnt fully solve it. The complete fix required: New purge valve, EVAP pressure sensor replacement, Fuel tank vent valve cleaning, New gaskets for the fuel cap The pressure sensor was actually the main culprit causing inaccurate air flow readings. After replacing these components, the fuel smell disappeared completely and the engine maintained stable idle. Fuel efficiency improved by about 2L/100km. Total repair cost was 410 Euro including labor. Given your mileage is similar to what mine was (around 150000 km), these components are likely at their service limit. Would strongly recommend having the entire EVAP and leak detection system checked rather than just replacing the purge valve. This prevents partial fixes that dont fully resolve the underlying issue.

Thanks everyone for the detailed responses. This really helps confirm my suspicions about the EVAP system failure. The pressure sensor replacement making such a big difference in air flow readings is especially relevant to my situation. I will schedule a complete system diagnostic to properly check all components rather than just replacing the purge valve. Based on the feedback, I will specifically request inspection of: EVAP pressure sensor, Activated charcoal filter, Fuel tank vent valve, All related gaskets The p0456 code combined with the fuel smell and stalling after refueling seems to match exactly what others experienced. Good to know the complete fix resolved both the check engine warnings and improved fuel efficiency. Will update once I have the full diagnostic results and know which specific components need replacement in my case.