Rough Idle & Stalling A8: Throttle Body Warning Signs

Experienced similar issues on a 2018 Audi A6 with the 3.0T engine. The symptoms match exactly what you describe, rough idle, hesitation, and check engine light. After diagnosis, it turned out to be a vacuum leak from a cracked hose connecting the brake booster pump to the intake manifold. The throttle body was initially suspected, but the real problem was the deteriorated rubber hose affecting proper air supply. These hoses commonly fail around 120000-150000 KM. The vacuum leak caused irregular air-fuel mixture, leading to the idle problems and hesitation. The repair required replacing the complete hose assembly and checking all related connections. This was a serious issue that needed immediate attention, as it affected both engine performance and brake system operation. If left unfixed, it could lead to complete engine stalling and reduced brake assist. The symptoms you describe strongly suggest a similar vacuum leak rather than a throttle body problem. Have the mechanic specifically check the brake booster hose connections and vacuum system integrity. These issues often trigger similar check engine codes as throttle body problems, but require different repairs.

Thanks for sharing your experience with the vacuum leak issue. My Audi had nearly identical symptoms and the manifold pressure readings were way off. Good to know about checking the brake booster hose, my mechanic initially thought it was the throttle body too and was about to replace it. Did you happen to remember the repair cost for the hose assembly and labor? Also curious if youve had any idle problems or engine stalling issues since the fix? Want to make sure this repair truly resolves everything before proceeding.

Since having the vacuum hoses and air valve assembly replaced, the engine has been running perfectly with no idle problems or stalling issues. The repair completely resolved those rough running symptoms. Total cost came to 175 Euro for replacing the defective hose connection from the pump to the valve. The air supply is now properly regulated and the check engine light has stayed off. Looking back, catching this issue early prevented more serious problems that could have developed with the vacuum system. Having a mechanic who correctly diagnosed the actual issue, rather than just replacing the throttle body, saved both time and money. The stable idle and smooth operation confirm it was definitely the right fix. These vacuum hose issues are quite common around this mileage point, so addressing it properly the first time means you likely won't face similar problems again for many years.

I finally got my car fixed last week and wanted to share my experience. The mechanic found a major vacuum leak exactly where you described, the hose between the brake booster and intake manifold was badly cracked. The check engine light was definitely pointing to an air intake issue. After replacing the complete hose assembly and checking all connections, the rough idle problems disappeared completely. The engine now runs smooth, with no more hesitation or stalling issues. Total repair cost was 320 Euro, which included full diagnostic testing and labor. Really glad I asked here first and knew what to tell the mechanic to check. Saved me from an unnecessary throttle body replacement that would have cost much more without fixing the actual problem. The car feels like new again and runs perfectly after addressing that vacuum leak.