Cadillac DTS Power Loss: Hidden Throttle Body Issues

Having dealt with a similar situation on my 2006 Cadillac CTS, I can share my experience as someone with moderate car repair knowledge. The reduced power and check engine light combo turned out to be caused by faulty chip tuning that a previous owner had installed. The car computer was showing multiple fault codes, making it initially tricky to diagnose. After scanning with a professional diagnostic tool, the workshop found that the aftermarket performance tune was conflicting with the factory ECU settings. The fix involved removing the modified tune and restoring factory settings, plus a complete system reset. Total repair cost was 180€, which included diagnostic time and reprogramming. The car ran perfectly after returning to stock programming. To better assist with your situation, could you share: What fault codes is your car computer showing? Has any performance tuning been done to your DTS? When did these symptoms first appear? Does the reduced power happen gradually or suddenly? Getting these details would help determine if your issue stems from a similar cause or if other components need inspection.

Thank you for sharing your case. At 144164 KM, I started experiencing the same problem after regular maintenance. I connected an auto scanner which showed P0068 and P0121 diagnostic codes. These seem to point toward either a throttle position sensor or mass airflow sensor issue. When the check engine light first appeared, the power loss was gradual over a few days before becoming more noticeable. The vehicle diagnostics also indicate irregular readings from these sensors which aligns with common issues in this model. Has anyone successfully fixed this by just cleaning the sensors before replacing them?

Thanks for those details, especially the fault codes. The situation with my CTS was quite similar, but in my case cleaning the sensors only provided temporary relief before the issue returned. The vehicle diagnostics showing those specific codes strongly points to the throttle body system. While cleaning the throttle position sensor helped initially, the check engine light returned after about 500km. The car computer continued showing erratic sensor readings until I eventually replaced both the throttle position sensor and the mass airflow sensor. The complete fix cost around 320€ for parts plus labor. After replacement, the engine power returned to normal and the dashboard light disappeared. My workshop explained that while cleaning can work temporarily, sensor degradation in these models often requires full replacement for a permanent solution. The irregular sensor readings you mentioned are a classic symptom. Before spending on new parts, you might try cleaning both sensors first, it's relatively simple and could save money if you catch the problem early enough. Just be prepared that thorough cleaning may only buy you some time before replacement becomes necessary. Would be helpful to know: Have you noticed any rough idling? Does the power loss seem worse in wet weather? Is the check engine light steady or flashing?

I appreciate all the guidance. After trying to clean both sensors this weekend, I definitely noticed some improvement, the check engine light temporarily went off and power seemed better. But you were right about it being temporary. The warning light came back on during my morning commute and the reduced power returned. To answer your questions: the idle is slightly rough especially when cold, the power loss seems consistent regardless of weather, and the check engine light stays steady rather than flashing. Given what you shared about your similar engine issue and sensor problems, I think I will go ahead with replacing both sensors rather than waste more time with cleaning attempts. The diagnostic codes are still showing P0068 and P0121, so at least the vehicle diagnostics are consistent in pointing to these components. Better to fix it properly now than risk further engine problems down the road. Will schedule the repair this week and hope for similar positive results with new sensors like you experienced.