So without knowing where to start I'll get right into it.
Two weeks ago my 2014 ECO (92,000 miles) had a check engine light come on. Diagnostic ran back a P0140 for low efficiency. Dealership said the catalytic converter has failed. Based on reading these forums and my very limited knowledge of cars in general from my understanding these things don't fail without another underlying issue. So anyways I take it to a recommended break and exhaust specialist (the dealer recommended) to do this. The mechanic there told me I ought to get the engine checked out to figure out what that underlying issue may be. He mentioned maybe that the injectors could be sticking. (I maybe have used the wrong terminology there). Upon replacement the check engine came back on. Took back to my dealership where they did another check that I believe was suppose to be a little more thorough. They came back to say the catalytic converter is smaller than the original causing issues with the turbocharger. I now do hear a whistling noise when I accelerate. The dealership recommended a tune up and a fuel induction cleaning on top of getting the converter issue corrected. So now I have the headache of playing phone tag between the dealership and the company they use routinely to fix these issues so I can fix a problem that may or not be there. I'm getting migraines from this and really starting to get put off from ever buying another chevy again.
Summary of issues:
*Catalytic converter-replaced (could be too small)
*Turbocharger-may or may not have problem based on whistling sound
*Underlying engine issue-waiting to get other aspects fixed first
Anyone have any recommendations outside of continually purusing the dealership to find the underlying issue??
Equally good question. From my understanding the dealership uses this third party themselves (with a markup I assume when the dealership passes it off to make some cash themselves). Whether intentional or not it saved me money which at this point hasn't been worth it.
The P0420 code and requiring a replacement catalytic converter has happened to a few 1.4T Cruzes. The automatics were actually recalled for it at one point to address so many of them being flagged/replaced...the manuals were not. The 1.4T runs VERY rich at wide throttle openings or under load...it keeps cylinder and exhaust temperatures down, but it raises cat converter temps through the roof.
A more hollow cat converter, as typical aftermarket ones are - especially if it is the one directly after the turbo - may make more of an audible turbo whistle due to less muffling of the sound. One changed the exhaust sound of my parents Accord slightly. Or it may be leaking exhaust where they did a bad install, which can confuse the downstream O2 sensor.
At this point, I would ask WHAT code they found specifically the next time, and decline the fuel injection cleaning service and tune-up for now. The codes now be resultant of an intake or exhaust leak.