SQ7 Tank Vent System Causing Stalling and CEL Issues

Had similar issues with my 2020 S6. The check engine light kept triggering due to a malfunctioning EVAP system. After diagnosis, the problem was traced to a clogged vapor line and a faulty purge valve. The pressure sensor readings were inconsistent, indicating a blockage in the fuel vapor recovery system. The fix required cleaning the EVAP system hoses and replacing the purge valve. While not a major mechanical issue, leaving it unaddressed can lead to poor fuel economy and potential engine damage. The stalling at idle is a classic symptom of this emission system problem. The repair took about 4 hours at the shop. Its worth getting this fixed promptly since a compromised EVAP system can cause increased emissions and fuel vapor leaks. The mechanics confirmed this is a known issue that can occur when fuel quality varies or after extended city driving with frequent short trips. Would suggest having the complete emission system checked, particularly focusing on the purge valve and vapor lines. The symptoms match exactly what happens when the tank ventilation system gets restricted.

Thanks for sharing your experience. This is reassuring as my Audi SQ7 had nearly identical symptoms. After getting it fixed last month, the engine light hasnt returned and the stalling issue is completely resolved. The pressure sensor and fuel tank ventilation were indeed the culprits. Quick question, do you remember roughly how much you paid for the repair? Also, has everything been working properly since the fix, or have you noticed any other emission system related issues?

Thanks for the follow-up. Happy to report that after getting the tank ventilation valve fixed, my emission system has been working flawlessly. The repair bill came to 175 Euro for clearing the clogged hoses, which was reasonable considering the diagnostic time involved. The EVAP system has been performing perfectly since the fix, no more engine lights, no stalling, and the purge valve is operating as intended. My fuel economy has actually improved slightly since the repair, which makes sense given the fuel tank ventilation system is now working correctly. One tip is to always ensure the gas cap is properly tightened after refueling, as this can help prevent similar issues from developing again. The emission system is quite sensitive, and even a slightly loose fuel tank cap can trigger those same symptoms we experienced. Haven been driving for about 8 months since the repair with zero recurrence of any emission-related problems. The investment in fixing it properly the first time definitely paid off.

Thanks everyone for your input. Taking your advice, I brought my SQ7 to a certified shop last week. The mechanic found issues with the tank ventilation system and a failing purge valve, just as suggested. The repair took about 3 hours and cost 320 Euro total. The check engine light has stayed off since the fix, and the car runs perfectly now, no more stalling at idle. They showed me the old parts, and the purge valve was definitely clogged. The pressure sensor readings are now stable according to their diagnostic report. The service included a full emission system inspection and cleaning of all vapor lines. Seems this was a common issue they had seen before. Really glad I got it sorted before it could cause any additional problems. The fuel economy has noticeably improved too, which is an unexpected bonus. For anyone else facing similar symptoms, definitely worth getting the tank ventilation system checked early rather than waiting for more serious issues to develop.