Colorado Diesel: Turbo Issues Causing Power Loss & Stalling

Had a similar issue with my 2019 Chevy Silverado diesel last year, was giving me the exact same symptoms you're describing. That whistling sound and power loss is classic boost system trouble. Got it fixed after the workshop diagnosed a faulty electrical bypass valve in the turbocharger system. Boost was leaking and the actuator valve wasn't regulating pressure properly. Total repair came to about 250 for parts and labor. Worth every penny, truck runs like new now. From what you're describing, sounds like you might have the same boost control issue, but would need to know: Any specific error codes showing? Does the whistling change with engine RPM? When exactly did these symptoms start? Any recent maintenance done? The Colorado and Silverado share similar turbo systems, so knowing these details would help nail down if you're facing the same boost leak problem I had. Best to get it checked soon, running with incorrect boost pressure isn't great for the engine long term.

Thanks for the detailed response. Just had my 5980 KM service done last month, and the issues started right after. To answer your questions, the whistling definitely changes with RPM and gets louder under load. Getting error code P0299, which points to the turbocharger boost control actuator fault. Haven't touched anything in the turbo system myself. The drop in boost pressure seems most noticeable when merging onto highways or climbing hills. The engine feels seriously down on power compared to how it ran before the service. Did your mechanic have to replace the entire actuator assembly, or just repair the electrical connection? Mine's still under warranty, but trying to understand what I'm dealing with before taking it in.

Definitely sounds like what I went through, especially with that P0299 code and symptoms starting after service. My boost issues also kicked in after routine maintenance, which turned out to be more than just coincidence. In my case, the techs found the actuator valve's electrical connector had gotten damaged during the service, someone hadn't clipped it back properly. The wastegate wasn't getting proper signals from the pressure sensor, causing the turbo system to malfunction. Unlike your situation, I was out of warranty, but the fix wasn't too complex. They didn't need to replace the whole assembly, just repaired the wiring connection and recalibrated the boost control system. The turbo wastegate started responding correctly after that. Quick tip: When you take it in, make sure they check the entire boost system pathway. Sometimes a small boost leak can cause similar symptoms, and it's worth having them verify all connections while they're in there. Had they done this during my service, might have caught the issue before it developed. Since yours is under warranty, definitely get it to the dealer. These symptoms are pretty clear indicators of boost control issues, and you shouldn't have any trouble getting it covered.

Thanks for all that detail. Makes perfect sense about the boost control system being affected during maintenance. Looking at my paperwork from the recent service, they did mess around with the turbo area while changing some filters. I've booked it in with the dealer for next week. They mentioned they'll do a full pressure test of the turbo system and check the actuator valve connections first. Good to know it might just be a wiring issue rather than needing the entire turbo actuator replaced. At least the warranty should cover whatever they find. Really hoping it's just a loose connection or minor boost leak like in your case. Will make sure they check all the turbo wastegate components and recalibrate the boost control system properly this time. Getting this fixed can't come soon enough, this lack of power and weird whistling is driving me crazy, especially on the highway. Plus, I'm sure running with messed up boost pressure isn't doing the engine any favors.