Hi guys,

I was talking to a friend of mine who works at a Mercedes Benz dealership. He's not a tech but he does work in the service department and he gets to talk with them quite frequently. He knows I have 997 and asked me about maintenance costs. I told him they were pretty reasonable but that I was kind of concerned about the cost of changing the batteries in the TPMS sensors when the time comes. He asked me if I was sure they still used batteries and I told him I thought so. He then went on to explain to me that Mercedes TPMS doesn't use batteries any longer it uses something he called transponding. As I said he's not a tech and he couldn't elaborate much more than that. Can anyone add to this? My last personal experience with Mercedes dates back to a 1999 E430 which didn't have TPMS.

Another question. ~IF~ the Porsche system still uses batteries and they "die" on me before the the tires need replacement would state inspection require me to get the batteries changed? In other words would I fail inspection if the TPMS in my car wasn't working?

My car doesn't get driven in the winter and I'm not putting that many miles on it in the other 3 seasons so if the TPMS uses batteries they will probably need replacement long before my tires do. I really don't want to shell out good money to have someone un-mount the tires from the rims just to replace the silly batteries. In my opinion that puts un-necessary wear and tear on the rims (tire machines can rip the sh*t out your rims regardless of how careful the techs try to be). I can easily live with a blank TPMS display but I can't live with my rims being ripped up just to change batteries in the TPMS.

Thoughts anyone?

 

they are self contained units, to replace a battery you would replace the entire sensor.

i believe the sensors go into "sleep" mode until the car is turned on and a signal is sent to the sensors... they are supposed to last a very long time and the porsche sensors are some of the nicest (tell you the exact psi, not just normal/low like most vehicles)

also our cars self learn automatically which means no trips to the dealer.

 

What does "very long time" mean in real time? Also, if and when they decide to stop transmitting can they be "ignored"? Do they do something really aggravating to make you want to replace the batteries? I seem to remember something like $500. to replace the power to the wheels.

 

TPMS sensors apparently can live up to 4 years (my car is about 5 years) and two of them died recently. They are not cheap (about $90 each) and can be bought from Tire Rack or your Porsche Dealer (much more expensive). They come with the full valve assembly.

Also, I do not believe that a TPMS alarm will prevent you from passing any State inspection as these alarms are not part of the list of issues that the DMV is tracking.

Again, I may be wrong but I encourage you to check with an inspection station.

I will soon purchase two replacement sensors to install on my 997.1 from Tire Rack, although the tires are still good for quite a few miles. I will have to open the wheels, replace the sensors and re-balance again.

Still, the best insurance against problems is to check the tires pressures at least once a week.

Yves

 

Thanks for your replies fellas. I kind of thought the whole unit had to be replaced. That kind of stinks but what can you do? I'll have to stop down at the inspection station and ask them, that's good adivce. I imagine there could be some variation about this from state to state.

I'm used to checking the tires the old fashioned way with my Snap-On gauge. My gauge is an old one from the 80's but it's one of those tools that is built for a lifetime of use. It was made in the USA and not in the slums of East Beijing as most items like this are today.

 

450/set including stems, so 100/ea sensor.

when they die, or break, or aren't in the wheels everytime you start the car it gives you a warning saying they aren't responding.. for first like 50 ft of driving.

 

http://en.wikipedia.org/wiki/Tire-pr...itoring_system

search the article for "battery-less" - interesting...