Audi A5 Fuel Tank Vent System Causes Engine Stalls

As someone with decent repair experience, I dealt with an identical issue on my 2016 Audi A4. The symptoms matched exactly, check engine light, rough idle, and system failure warnings related to the EVAP system. The problem turned out to be a defective activated charcoal filter, which is a critical component of the emission control system. The pressure sensor readings were all over the place, causing the engine management system to get confused. Got it fixed at an independent workshop specializing in VAG cars. The total repair cost was 275 Euro, including parts and labor. The fuel efficiency improved noticeably after the repair, I was burning about 15% more fuel before getting it fixed. The repair process took about 3 hours. They had to remove some undercarriage components to access the charcoal filter assembly. After replacement, they ran a complete EVAP system diagnostic to ensure everything was working correctly. Could you share: Current mileage on your A5? Are you getting any specific error codes? Have you noticed any fuel smell, especially when filling up? When did the symptoms first appear? This information would help determine if your issue is identical to what I experienced.

Last service was done at 77000 KM, currently at 79357 KM. Thanks for sharing your experience. The leak detection warning appeared right after I noticed a strong fuel smell. The error code reader shows P0456, indicating a small EVAP system leak. Fuel consumption has increased by roughly 2L/100km since these issues started about 2 weeks ago. The smell is particularly noticeable when refueling, just as you mentioned. Looks like I might be dealing with the same charcoal filter problem. I will contact a workshop to check the pressure sensor readings and run a complete system diagnostic.

Thanks for providing those details. The P0456 code and fuel smell match exactly what I experienced with my A4. After seeing your symptoms and error code, I'm even more convinced it's the same charcoal filter issue. The increase in fuel consumption you mentioned (2L/100km) is very similar to what I experienced before getting the repair. The strong fuel smell during refueling is a classic sign of the EVAP system not properly processing fuel vapors through the purge valve. When the workshop checked my car, they found that the activated charcoal filter had deteriorated, preventing proper fuel tank pressure regulation. The EVAP system leak was causing both the error code and the efficiency drop. The good news is that once fixed, all symptoms disappeared immediately. My fuel consumption returned to normal, and the check engine light cleared after the system diagnostic. The repair has been reliable with no recurrence of issues. One tip: make sure they check the purge valve while they're in there. In my case, it was still good, but it's worth inspecting since accessing these components requires similar labor time anyway.

I greatly appreciate all this detailed feedback. Your experience matches my situation so closely it's giving me confidence about the repair path. Based on the fuel efficiency loss and error codes being identical, I'll definitely have them inspect both the charcoal filter and purge valve during service. The EVAP system leak has clearly been affecting my fuel consumption significantly, and I want to get this resolved before any potential system failure causes more serious issues. I've scheduled an appointment for next week with a workshop that specializes in these repairs. I will make sure they conduct a complete diagnostic of the fuel tank ventilation system while they have everything opened up. The smell during refueling and the P0456 code really point to the charcoal filter being the culprit, just as in your case. The quoted repair cost also seems reasonable compared to what you paid. Thanks again for sharing such specific details about your repair experience. It helps tremendously in knowing what to expect during the service visit.