A2 Stalling & Weak Power: Failed Fuel Regulator Alert

After replacing the fuel filter on my A3 1.8T from 2003, I encountered similar symptoms. The check engine light came on immediately, accompanied by rough idling and weak acceleration. The issue turned out to be more complex than just the fuel pressure regulator. The main problem was a combination of trapped air in the fuel system and a failing fuel pump. When changing the filter, air entered the fuel lines, causing pressure drop across the system. While bleeding the lines resolved the initial symptoms, the persistent check engine light revealed the underlying fuel pump issue. The repair involved: Complete fuel system diagnostics, Bleeding air from fuel lines, Fuel pump replacement, Clearing error codes This was classified as a serious repair since the fuel efficiency dropped significantly and continued driving could have damaged other components. The symptoms matched exactly what you describe, stalling at idle and poor acceleration. Key warning signs were: Consistent pressure drops, Fuel pump making unusual noises, Irregular idle speed, Drop in power under load Recommend getting a proper fuel system diagnosis before replacing individual parts. The pressure regulator might be involved, but testing the entire system will save time and prevent misdiagnosis.

Thanks for sharing that detailed experience. That really sounds similar to my situation with the rough idle and engine misfire problems. My A2 is showing those exact same symptoms now. Did you remember roughly how much you ended up paying for the complete fuel system repair? Also curious if youve had any related issues pop up since getting it fixed? Trying to budget for repairs and want to make sure I address everything properly the first time around.

Thanks for asking about the follow-up costs. Actually after getting it properly diagnosed, the repair was much simpler than my initial post suggested. The main culprit was indeed a defective fuel pressure regulator, which caused the engine misfire and rough idle symptoms. The mechanic found no issues with the fuel pump after running diagnostics. After fixing the pressure regulator and clearing the check engine light following the fuel filter change, the total came to just 45 Euro. Much less than I initially feared. The car has been running smoothly for months now with no fuel efficiency issues or engine misfires. The idle is stable and acceleration is back to normal. Having the proper diagnosis done first definitely saved money by avoiding unnecessary parts replacement. My suggestion would be to start with having your fuel pressure checked. The symptoms really point toward pressure regulation problems, which could be a straightforward fix like mine turned out to be.

I took my car to a new mechanic yesterday after reading these replies. Really glad I did, they found the issue quickly. Just like suggested, they first tested the fuel rail pressure and found it was way below normal. The fuel pressure regulator was definitely shot. Total repair came to 180 Euro including parts and labor. The mechanic also cleared the check engine light and did a test drive to make sure everything was fixed properly. Car runs perfectly now, no more rough idle or stalling issues. What a relief to have it sorted without replacing the entire fuel pump or other expensive parts. The diagnostic approach definitely saved me money. Really appreciate all the advice here that helped me understand the issue before going to the shop. Just took it for a proper drive and the engine response is completely back to normal. No more misfire symptoms or acceleration problems. Should have done this weeks ago instead of worrying about finding the right mechanic.