Tire pressure sensor system failure

Try resetting it-could be a sensor problem

TIRE PRESSURE MONITOR WARNING INDICATORS

When the tire pressure warning light illuminates and warning message appears on DIC, immediately check air pressure of all tires and adjust to the specified pressure. If warning indicators are still on, there is a problem in the TPM system. See appropriate manufacturer service information.
TIRE PRESSURE SENSOR RELEARN
NOTE:In the following procedure, a TPM Sensor Activation Tool (J-46079) must be used.

NOTE:If the tire pressure sensor or RCDLR is replaced, the TPM system needs to relearn tire pressure sensor IDs.

Description & Operation
The TPM system uses the RCDLR, BCM, keyless entry transmitter, 4 radio frequency transmitting pressure sensors, and the serial data circuit to perform the TPM learn mode functions. The sensor learn procedure must be performed any time the RCDLR or a tire pressure sensor is replaced. Once the learn mode has been enabled, each of the sensor's unique identification (ID) codes can be learned into the RCDLR's memory. When a sensor's ID has been learned, the RCDLR sends a serial data message to the BCM to sound a horn chirp. This verifies the sensor has transmitted its ID and the RCDLR has received and learned it. The RCDLR must learn the sensor IDs in the proper order to determine correct sensor location. The first learned ID is assigned to left front, the second to right front, third to right rear and forth to left rear.
Each sensor has an internal low frequency (LF) coil. When the TPM Sensor Activation Tool (J-46079) is used in activate mode it produces an LF transmission that activates the sensor. The sensor responds to an LF activation by transmitting in learn mode. When RCDLR receives a learn mode transmission while in TPM learn mode, it will assign that sensor's ID to the location on the vehicle relative to the order in which it was learned.
The TPM system will cancel the learn mode if more then 2 minutes have passed and no sensors have been learned, or if the RCDLR has been in learn mode for more than 5 minutes. If the learn mode is canceled before any IDs are learned, the RCDLR will remember all previously stored IDs and their locations. As soon as the first sensor ID is learned, all other IDs are erased from the RCDLR's memory.
Turn ignition switch to ACC position. Apply parking brake.
Simultaneously press the keyless entry transmitter's lock and unlock buttons (05-07 models), or using the scan tool, initiate the TPM learn mode (08-09 models), until a horn chirp sounds, indicating the learn mode has been enabled.
Starting with left front tire, hold antenna of TPM Sensor Activation Tool (J-46079) against the tire sidewall close to the wheel rim at the valve stem location, then press and release the ACTIVATE button and wait for a horn chirp.
After horn chirp has sounded, proceed as in step 3 for the next 3 sensors in the following order: right front, right rear and left rear.
After left rear sensor has been learned, a double horn chirp will sound, indicating all 4 sensor IDs have been learned. Turn ignition switch to OFF position.