I get this error code when it's extremely hot out and within 2-5 minutes after turning on the AC. I bought my 2019 Equinox Premier Sept 2023 at a dealership 3 hrs from when I live. It was hot out and when we got home that night the car was smoking and leaking oil everywhere. Took it to a dealership here and found the vacuum pump seal was blown. Dealership I bought it from paid to have it fixed but since then when I turn on the AC that code comes up and get underboost off engine only. I hook up my code reader and that's only code so I turn off AC and clear code then car runs fine. So is there something blocking the vacuum pump to the intercooler or is the turbocharger freezing causing intercooler to freeze.