RS6 Engine Stalls: Fuel Tank Ventilation Issues Exposed

Interesting timing, dealt with almost the exact same issue on my 2019 RS4 last month. Have some experience working on VAG engines, though mainly basic maintenance. The symptoms match what I experienced, check engine light and rough idle. The pressure sensor readings were inconsistent, suggesting a ventilation system problem. After using specialized leak detection equipment, the workshop confirmed a defective activated charcoal filter was the culprit. The air flow through the emission system was completely compromised. The repair took about 3 hours total, including diagnostic time. Total cost was 275 Euro including parts and labor. Since the fix, the engine runs smoothly and no more warning lights. To provide more specific advice about your case: What diagnostic codes is the check engine light showing? Have you noticed any fuel smell? Does the problem get worse after refueling? Has the purge valve been tested with proper diagnostic equipment? These details would help determine if your issue is identical to what I encountered. The activated charcoal filter failure is common in this engine family, but its worth confirming with proper diagnostics before replacing parts.

Last service was at 80000km, just before these issues started. The diagnostic codes point to P0456 and P0441, which are indeed related to the EVAP system. No fuel smell detected, but the stalling gets noticeably worse after refueling. The purge valve testing was only visual, no specialized diagnostic equipment was used yet. The check engine light has been intermittent, typically appearing after longer drives. Worth noting that the leak detection pump seems to be making more noise than usual during its self-test cycle. Will get the pressure sensor readings checked properly at the workshop next week.

Thanks for the additional details. Those diagnostic codes match exactly what I saw on my RS4. The P0456 small leak detection issue, combined with the P0441 EVAP system malfunction, strongly points to a failing activated charcoal filter, just like in my case. The increased noise from the leak detection pump is particularly telling. When my charcoal filter was failing, the system was working harder to maintain proper fuel tank pressure, causing similar symptoms. Interestingly, my fuel efficiency dropped about 8% during this period. Did you notice any changes in your fuel consumption? The compromised emission control system can definitely impact overall engine performance. One quick test you can try before the workshop visit: listen for a clicking sound from the leak detection pump after turning off the engine. A normal pump should run quietly for about 30 seconds. In my case, it ran much longer and louder, which was a clear indicator of the system trying to compensate for the leak. Based on the similarities to my repair experience, I expect youll need the same fix, new activated charcoal filter and possibly some associated seals. The repair should be straightforward for any VAG-experienced technician.

Thanks for providing those specific codes and information about the leak detection pump noise. The P0456 and P0441 codes definitely align with the emission control system issues you described. The worsening symptoms after refueling are a classic sign of EVAP system problems. Given my experience with the activated charcoal filter replacement, I plan to have the workshop do a complete system diagnosis. The intermittent check engine light and stalling match the pattern you saw with your RS4. Ill make sure they specifically check the pressure sensor readings and do proper purge valve testing with diagnostic equipment. Good point about monitoring the leak detection pump noise. Ill pay attention to the running time after shutdown tonight. The fact that my issues started shortly after the 80000km service is probably relevant for the diagnosis too. Your repair timeline of 3 hours seems reasonable, so Ill plan accordingly when scheduling the workshop visit next week. Thanks for sharing your experience, it helps confirm Im on the right track with the system failure investigation.