TPMS Really works
 

Situation: Driving along and the TMPS warning came on and dash screen showed left rear tire was low. I thought this was interesting insofar as the car has only 1900 miles and I don't remember driving over anything bad. Anyway, went to service station and topped up air pressures all around. We've had a spate of cold weather; as a consequence I thought that the tire pressure went down just enough to trip the TPMS. Later, I walked around the car and found a sheet metal screw in the tread. Went to tire service station and had the tire repaired.

Of interest, I noticed that the wheel did not have a TPMS sensor located inside. The service tech said that there is some type of sensor located inside each wheel, but not on it, that can measure the tire's inflation. Don't know how, but I know it works!

It uses the ABS sensors to recognise one wheel is turning faster than the others, so must have a smaller circumference due to a flat. The is no sensor in the wheel at all - the pressure is not measured directly.

+1
 

Older US Q5's and some other Q5's in other geographies use the internal wheel sensors, but recent year Q5's in the US have eliminated the sensor in favor of the cheaper ABS indirect system.

Audi uses two systems

http://www.audi.com/com/brand/en/too...m.browser.html

Audi stopped using direct sensor TPMS in most U.S. MY2010 models in favor of the indirect/ABS system. The A8/S8/R8 are exceptions.

I think it's the same with models RS6 and RS7 - that they have sensors

R8 has the most expensive system, RS7 most complicated

Now we know how it works and I can attest to the fact that it works quickly too. I hit something on the road. All 4 of us in the car heard it rattle in the left rear wheel well. Within a few seconds the TPMS light was on and by the time I got across the lanes of traffic and stopped, the tire was flat. Steve

How funny. I had a very similar situation at Christmas. We were at 2200 miles, right rear, and it was a deck screw. I did not see a specific tire on the TPMS, but it did come on. Same as you, I thought that it was weather relate until I checked them. The local tire dealer would not repair because of the peelers (afraid to scratch them). I had to take it back to dealership.

It does work surprisingly well. I went mountain biking and I apparently picked up a small nail in my rear right tire. The TPMS went off so I pulled right over and it was a slow leak but definitely damaged. This was on Christmas eve day and everywhere was closed. It was also on my BRAND NEW winter Pirellis with the car having <1000 miles and tires <200 miles. I didn't want to do the spare so I called Audi Roadside to see if someone could just come out and patch it but nope, they can't do that. They can however help me put my spare on. :rolleyes:

I knew I wasn't going to get it fixed for a few days and needed the car so I had my wife bring out a stock summer wheel/tire and I put that on. lol Two days later Discount Tire plugged it.

Our TPMS went off recently; due to over-inflation by the way from service work; but it didn't indicate which tire. Are you able to get which tire? If so, I couldn't figure it out. And since, in our case, no tire was low, I had to check each and every tire. 50 PSI in the serviced tire by the way!!