is there a battery in each unit at the valve stem that wears out? and a friend of mine has a set from a 991 that are new, will they work in my car?

 

Yes, the battery life is about 4-5 years.
Your friend's set will work if it is fresh (battery wise) and if the set is of the early protocol. Second generation 997.2 use a different protocol and are not compatible with the early one (997.1).

Yves

 

There are several frequencies or protocols used, and the transponders must be compatible with the receivers in the car's wheel-wells.

 

so could i change the receivers or is that more expensive and difficult than just getting new senders... or just let them fail and check tire pressure with a good old fashioned ....jeez, whaddya call them anyway, y'know, they look llike a pen, keep one in my door space always anyway, old age is creeping in to my vocabulary... i can see it and can see the 'door space', which i can't name either at the moment, but my typing is getting better the more i ramble on about this sh8t

 

My wife calls it a "thingy." She also calls lots of other stuff "thingy."

Question - Is it a good idea to change out batteries when the tires get replaced?

'Nother question - Anyone know the watch battery size for the transmitters?

 

Yes, is a good idea only because you're not overlapping labor but I would only replace them only if the battery life is less than 24 months. Could be simply check with a PIWIS tester, 5 mins deal.

NOTE: From past experience we start seeing issues with the sensors 24months or less.

 

Batteries are sealed in - can't be replaced.

 

By "replace them" you mean replace the sensors correct...since the batteries can't be replaced.

 

Yes, I didn't make myself clear. Replacing the batteries = replacing the sensors

 

well for 500€+/-, i can check my own tire pressure, dare i say it, just as well, maybe even BETTER than these little enviornmental hazards... maybe i will take one apart and try renewing it... they always say, like the 'lifetime' transmission fluids in audis, we'll see

 

I use a manual gauge to check tire pressures but I like having the TPMS to let me know that pressures are holding steady while driving and that I don't have a slow leak that might turn into a flat.

 

Its handy to use on the fly to see the differences in cold and hot temperatures.
Ill be checking it again on the way home from work today when the sun is out as im working on my tyre pressures for comfort reasons ......

 

now if you could regulate tyre pressures from the ****pit...

 

Can you get the fault code to go away if you decide not to replace them?

 

It can be done but not easily - you have to get the dealer techs involved. Someone on the GT3 board (search Mooty) posted the process 3 years or so ago. Otherwise you just have to live with the warning light.