TPMS Monitor seems Unreliable
 

Wow! I have not seen this "Ask a Question" feature before. Thanks!
My 2007 Base A6 Coupe had a chronic "Left Rear Tire Low" warning for several months. Checking the tire pressure manually indicated the pressure was usually correct, but occasionally that tire was indeed low. Now with new Wheels, new Tires and all new TPMS Sensors, again there is a chronic "Left Rear Tire Low." These new tires are absolutely correct. Also, for an hour or so of driving, all tires showed XX pressures and I had a DIC "Check Sensor System" warning. And, the old tires show Tire Wear in the Center of the tread ... indicating the pressure was Too High. What is wrong with my TPMS sensor system?

Do you have a cell phone sitting it the cup holder? This is known to interfere with the TPMS. Happened to me on a trip to Florida, got XX pressures, stopped and checked, no problem. All week in FL no problem. Driving home got the XX pressures again. Turned out it was my brother riding shotgun using Waze on his cell phone and putting it in the cup holder.