Fuel Pump Folly for Chevy Silverado
This bulletin applies to 2014-2019 Chevy Silverado trucks. The vehicle may have a concern with a Service Engine Soon (SES) lamp on and a rich running condition DTC P0172 and P0175. The cause may be the high pressure fuel pump. If routine diagnostics do not isolate the cause, the following may be helpful:
Disconnect the dirty air 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. Chevrolet reports that with this concern, they do not see a lot of fuel in the crankcase, so changing the 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.