My car is displaying "reduced engine performance" fairly frequently. on 2011 Volvo C70

The car goes into limp mode with the warning. Dealer replaced the Throttle Body. Got it back today and it did the same thing. Electronic or mechanical problem? Air injection relay? Any ideas?

Asked by for the 2011 Volvo C70
It's really impossible to know what is causing this without performing a few dianstic reading the codes, checking all the intake hoses etc. If the dealer just worked on it then I would return as it should be a warrantied repair.