DeVille Engine Mount Issues Causing Rough Idle Problems

I dealt with a similar vibration issue on my 2006 Cadillac DTS last year, and I have some experience working on these cars. The symptoms you describe match what I experienced, excessive vibrations at idle that got progressively worse. In my case, the mounting bracket had a loose connection causing the engine mount to not properly dampen vibrations. The workshop found that the cable connection to the active engine mount system was damaged, leading to the mount failure. The repair involved replacing the wiring connector and testing the engine mount functionality. After fixing the connection, the vibration issues were completely resolved. Including parts and labor, the total came to 95€. Before jumping to conclusions though, I would need some additional details about your specific situation: Have you noticed any clunking sounds when accelerating or braking? Does the vibration change intensity when putting the car in drive vs reverse? Can you share the specific error code that was stored? This information would help determine if your symptoms truly match the motor mount issue I experienced or if there might be other factors at play. The active engine mount systems on these models can be tricky to diagnose without complete information.

Latest service was 3 weeks ago at 186358 KM. The vibration issues have definitely gotten worse since I posted. To answer the questions: yes, there are noticeable clunking sounds during acceleration and gear changes. The vibrations are most intense in drive, less in reverse. The error code is P0117. After checking the workshop manual, the failed mount symptoms match perfectly. The engine clearly shifts more than normal when under load, indicating a defective engine mount. My mechanic confirmed significant wear on the passenger side motor mount during a quick inspection. Seems like a straightforward mount replacement job is needed based on the feedback so far. Will schedule the repair next week and report back on whether this resolves the vibration problem.

Thanks for the additional details about the symptoms. The clunking during acceleration and the more intense vibrations in drive definitely align with my mount wear experience on the DTS. When my mount failed, I also had that characteristic engine movement under load. The P0117 code can sometimes appear alongside mount issues due to the vibrations affecting sensor connections, which is exactly what happened in my case. Just a heads up, while changing my passenger side motor mount fixed the main vibration problem, we discovered the transmission mount was also showing early signs of wear. The shop recommended replacing both the engine and transmission mounts as a set since they tend to fail around the same mileage point. I went ahead with both and the total repair came to 450€. The complete mount replacement made a huge difference in overall smoothness, far better than just fixing the obviously failed mount. Worth considering while the car is already in the shop, especially at your mileage which is very close to what mine was when the mounts started failing. Looking forward to hearing how the repair turns out for you. The symptoms are nearly identical to what I dealt with, so a mount replacement should sort out those vibration issues.

Thanks everyone for the helpful feedback. After monitoring the symptoms these past few days, I'm now completely convinced we're dealing with a rubber mount issue. The vibrations have gotten even more pronounced, especially during gear changes. I took your advice about checking both mounts while the car is being serviced. Called my mechanic and scheduled a full inspection of all motor mounts for next Tuesday. Given the mileage and how the engine is shifting under load, replacing both the engine and transmission mounts makes sense to prevent future problems. Got an estimate of 475€ for replacing both mounts, which seems reasonable based on the costs others shared here. Will definitely post an update once the failed mount is replaced to confirm if this resolved all the vibration and clunking issues. The stored P0117 code is still present, but hopefully addressing the mount failure will take care of that too since several of you mentioned sensor connection problems caused by excess vibration. Thanks again for helping diagnose this mount wear situation.