Tire pressure sensors
 

A few days ago I put a set of four 19 inch OEM wheels (taken from a 2005 A8L) on my A8L. While putting 4 new tires on those wheels, I checked the tire pressure sensors and they seemed to be fine (just from looking @ them) but now those sensors do not communicate with the car's board computer and when I turn the tire pressure monitoring on (on the the display) it shows alarm, saying check the tire pressure! Even with the old OEM 18 inch wheels I had before it was the same problem. I was hoping the problem would go away when I upgrade the wheels to 19 inch!

Any idea what could be wrong with it? Is that the board computer or any thing else is wrong?

Thanks for your help.

A.

TPMS systems are very hard to diagnose, and they throw temper tantrums if you mess with it. You did have the sensors installed into the new wheels right? Did you check the spare tire to see if its flat?
I do know there is a 20 minute drive cycle after storing the pressures before it will display on the screen. In other words store the pressure on go on a 30 minute cruise, and see if the pressures show up on the screen. If it doesn't you need to hand the car over to someone that has a VAG COM or a dealer technician.