Audi Q7 Rough Idle Points to Failing Fuel Sensor

I faced a similar issue with my 2013 Audi Q5 3.0T about six months ago. Having some experience working on fuel system issues, I initially thought it was something major when the check engine light came on and the engine misfire started causing that distinct rough idle. After taking it to my workshop, they diagnosed the problem as a loose connection in the wiring harness connected to the fuel pressure sensor. The faulty connection was causing irregular fuel delivery readings, which made the engine management system behave erratically. The total repair cost was 95 Euro, mainly for diagnostic time and fixing the connection. The symptoms you describe, especially the jerking during acceleration and rough idle, match what I experienced. However, to provide more specific guidance, could you share: Have you noticed any fuel consumption changes? Does the rough idle happen more when the engine is cold or warm? Have you recently had any other repair work done near the fuel system? Did you scan for specific error codes when the check engine light appeared? These details would help determine if your issue is similar to what I encountered or if it might be something else in the fuel delivery system.

Thanks for the responses. At my last service at 83990KM, everything was fine, but these issues started shortly after. The fuel economy has definitely gotten worse, using about 2-3L more per 100KM than usual. The rough idle mostly happens when the engine is warm, and it seems worse after the car sits for a while. Had no previous work done on the fuel system. Used a basic scanner that showed P0087 code, fuel rail pressure too low. Really hoping its just the fuel pressure sensor and not the entire fuel pump assembly that needs replacement.

Thanks for those additional details. Based on that P0087 code and your symptoms, especially the increased fuel consumption and warm engine rough idle, I think your issue might be more complex than the wiring problem I had on my Q5. When I dealt with similar symptoms, I decided to have the entire fuel system diagnosed properly. While my initial problem was just a loose connection, I later learned these symptoms often point to either a failing fuel pressure sensor or a weakening fuel pump. The fact your issues worsen after the car sits suggests fuel pressure is not holding properly. The fuel injectors could also be a factor here, since improper fuel rail pressure can affect their operation. In my case, once they fixed the sensor wiring, they also cleaned the injectors which helped restore normal fuel economy. Given your Q7 has over 80000KM, I would suggest getting the fuel pressure tested properly. The basic scan showing low rail pressure means something in the fuel delivery system is definitely compromised. While a sensor replacement might fix it, you want to rule out pump issues before they leave you stranded. Currently having your car perform a fuel pressure test would be the smartest move. When my sensor connection was fixed, it cost under 100 Euro, but if you need the entire sensor replaced, expect around 300-400 Euro. A fuel pump assembly would be significantly more expensive.

Thanks everyone for your input. I really needed this advice since the car has been giving me such headaches lately. I went ahead and booked an appointment with a local shop that specializes in fuel system diagnostics. Given the P0087 code and the fuel economy issues everyone mentioned, I agree it makes sense to get a proper pressure test done first before replacing any parts. The fact that the rough idle gets worse when the engine is warm and after sitting definitely has me concerned about the fuel pump, but I'm hoping it turns out to be just the sensor. Will update once I get the diagnostic results and know the actual repair costs. Really hoping to avoid that expensive fuel pump replacement! In the meantime, I'll keep an eye on the fuel consumption and try to avoid situations where the engine might stall. Thanks again for helping me understand what I'm dealing with.