You shall start and idle the engine in PARK for 3 minutes, monitor desired and actual RPM, then the ECM will start to learn the new idle cells and Desired RPM should start to decrease. And you shall turn the ignition OFF for 60 seconds, and start and idle the engine in PARK for 3 minutes, after the 3-minute run time, the engine should be idling normally. After the drive cycle, the engine should be idling normally. Once the engine speed has returned to normal, you shall clear DTCs.
By BobGM Specialist
02/11/2022