I also cannot find any information on the U1273. That appears to be a incorrect code. This can happen when using aftermarket (Snapon) scanners as they do not often correctly communicate with the computers.
However, it is possible that you have either a bad sensor or a system that is not waking up correctly.
If you follow the procedure in this TSB it will help you to isolate the concern.
ISSUE:Vehicles built with the tire pressure monitoring system (TPMS) sensors may experience a concern where the TPMS indicator is on solid and the message center (if equipped) displays "Low Tire Pressure". This may be due to the actual tire pressure being low due to time or temperature changes (10° = 1 psi). Adjusting the tire pressure to specification should turn out the warning light once the sensors have been awakened.ACTION:If the vehicle has been stationary for more than 30 minutes, it will be necessary to wake up the sensors with the training tool to force them to transmit the latest air pressure information to the smart junction box (SJB), or responsible module. This can be done by either driving the vehicle for 2 minutes above 20 MPH (32 Km/h) or by using the training tool. The sensors do not continuously transmit when the vehicle is not moving.NOTE: ADJUSTING THE TIRE PRESSURE IS NOT A WARRANTABLE ITEM. SERVICE PROCEDUREInflate all tires to the correct air pressure. Place the ignition in the RUN position. Use special service tool 204-324 for valve-mounted TPMS sensors or 204-363 for wheel mounted sensors. Place the magnet on each sensor for approx. 5 seconds or ping each sensor at least twice after adding air to ensure the module has the latest air pressure data. If the TPMS indicator does not go off after filling the tires to the correct air pressure and pinging each sensor then that sensor is probably failed.
The magnet that I use is a round magnet that will just fit around the valve stem. A good example is the magnet that is in the transmission pans of most vehicles.