How to remove the Check Air pressure message from 2007 GMC Sierra?

Question

but it doesn't need any more air. How do you reset it w/o having to go to the dealer?

Answer 1

If the CHECK TIRE PRESSURE message is displayed on the DIC and the low tire pressure indicator is displayed on the IPC. Both the message and indicator can be cleared by adjusting the tire pressures to the recommended psi.

EDIT.

OK,a little involved, but here goes.

Ignition ON,

•  On vehicles equipped with keyless entry, simultaneously press the keyless entry transmitters lock and unlock buttons until a double horn chirp sounds indicating the Learn Mode has been enabled.  

•  On vehicles not equipped with keyless entry, press and release the driver information center (DIC) INFO button until the TIRE LEARN message appears on the DIC display. Press and hold the SET/RESET button until a double horn chirp sounds indicating the Learn Mode has been enabled.

Start with the left front.

Increase or decrease the tire pressure for 8-10 seconds then wait for a horn chirp. The horn chirp may occur before or up to 30 seconds after the 8-10 second pressure increase/decrease time period has been reached. Once the horn chirp has sounded, the sensor information is learned  Do the same procedure for the other three in order... R/F--R/R--L/R.

When the L/R has learned, a double horn chirp will sound indicating all sensors have learned.

Turn ignition OFF.... adjust tire pressures to specs.

Answer 2

If the tire pressures are correct as you said in your question then one of the TPM sensors may have failed, or they may just need to be reprogramed.  Most tire shops have the tool to reset the sensors if you dont want to go to the dealer. The dealer will have the correct tool and usually someone who can take care of this easy problem quickly.