I had 4 tires replaced on 2004 mercury mountaineer. When I left, I had tire pressure sensor fault. Went back, they told me I now had a broken sensor. They replaced sensor, and still had fault. They told me to drive around for couple of days to see if went away. It did not... Found out the tires sensors need to be re trained. I am not a mechanic, and was able to do. To do - turn ignition on and off 3 times, when on the 3rd time, press brake pedal, then ignition on and off three times, leaving on 3rd time. Horn beeps, and follow instructions on panel. You need a magnet, and start with driver front tire. Place magnet around stem, wait a few, horn beeps, and panel will tell you to go to next one, passenger front, do same thing with magnet, horn beeps, panel tells you to go to rear pasenger tire and finsh with driver rear tire. This worked for me, so good luck to anyone having problem.