Chevy Corvettes are Running Rich
This bulletin applies to 2016-2019 Chevy Corvette vehicles equipped with a 6.2L LT1, LT4 or LT5 engine. The vehicle may have a concern with the SES lamp on and a rich running condition.
DTCs P0172 and P0175 may be stored. If normal diagnostics does not isolate the cause of the rich condition, disconnect the dirty side of the PCV system.
Plug the vacuum supply. Start the engine and monitor the fuel trim in closed loop. If the fuel trims return to normal, this is a good indicator that the high pressure fuel pump is leaking. With this concern, you will not see a lot of fuel in the crankcase, so changing the engine oil may not isolate the concern.
When the high pressure fuel pump leaks, the PCV will pull the fuel mist straight into the intake, causing the concern.