T-Roc Engine Light + Rough Idle Points to Throttle Issue

As a VW Golf 2017 owner, I encountered nearly identical symptoms. The rough idle and check engine light pointed to a vacuum leak, which turned out to be a deteriorated hose connection between the brake booster pump and air valve. The symptoms matched perfectly, unstable idle, especially when the engine was cold, and occasional stuttering. While this might sound minor, vacuum leaks can cause serious engine performance issues and increased fuel consumption if left unaddressed. First step should be checking all vacuum hoses near the air intake system. Look for cracked, loose, or damaged hoses. A vacuum leak test using smoke will reveal the exact location. In my case, the repair involved replacing the faulty hose connection and recalibrating the air intake system. The issue requires proper diagnostic equipment to pinpoint the exact location of the leak. A thorough mechanic should perform: Complete vacuum system pressure test, Air intake inspection, Throttle body cleaning, Computer diagnostic scan This isnt a problem to ignore, as vacuum leaks can affect multiple engine systems. Getting a proper diagnosis from a shop with the right diagnostic tools is essential.

Thanks for sharing that fix for the vacuum leak problem. My situation sounds really similar. The rough idle and leak test was exactly what helped diagnose my T-Roc too. It turned out my throttle body was quite dirty and several vacuum hoses needed replacement. Do you remember roughly how much you paid for the full repair? Also curious if you had any other check engine warnings or idle problems come up since getting it fixed?

Thanks for asking about the follow-up. After having the vacuum leak fixed on my Golf, the engine has been running perfectly smooth with no idle problems or warning lights. The repair cost came to 175€ for replacing the defective hose connection between the pump and air valve. The investment was worth it since the engine stalling and rough idle issues completely disappeared. The air supply system now works exactly as it should, and fuel consumption returned to normal. Having a skilled mechanic properly diagnose and fix the vacuum hoses made all the difference. I recommend getting these kinds of vacuum leak issues addressed quickly, as they can lead to bigger problems if ignored. But once fixed properly, they typically dont come back. Its been over a year now with zero engine performance issues or warning lights.

I followed your mechanic's advice and went to get it checked at a different shop. The diagnosis confirmed exactly what you mentioned, dirty throttle body and worn vacuum hoses. The repair took about 2 hours and cost 220€ total, including parts and labor. The check engine light cleared right after the fix, and the rough idle completely disappeared. The mechanic did a thorough job checking the entire air intake system and found two cracked vacuum lines I never would have spotted myself. The air valve was also cleaned as a preventive measure. Been driving for about 3 weeks now and the engine runs perfectly smooth. No warning lights or idle problems since the repair. Really glad I got a second opinion and had it properly diagnosed this time. The air supply system works great now, just like when the car was new.