My 2008 Passion suddenly lost air pressure in the front left tire this morning at 100 kph. I safely made the shoulder of the highway. On inspection I found the entire valve missing. Smart move got me back to the dealership (prompt service, kudos!) where it was determined that all 4 sesors have to be replaced, but at my cost, out of warranty at 104,000 kilometers. While waiting I noticed the new 2011 Smart Passion has a different sensor all rubber! Those of you with alloy wheels watch for splits in the silver plastic nuts, first sign of corrosion on the valve body. This has the making of a safety recall, I was lucky to be on a straight dry road with light traffic and have the training to know how to handle sudden tire loss. It could have been much worse.
Oh Joy! Just what I wanted to hear; a safety issue to boot. First of all, I hate those flimsy plastic caps. They are hard to get on and off and if you drop them, just try to find them on the pavement!! I have had problems with getting them off; had to have the husband get it off and I don't tighten them way down either. This morning (a cold one) my low pressure light was on so I stopped at the gas station to check all the pressures. I had problems again trying to get that same cap off. It seems to me the threads on the tire stem are corroding.
Any suggestions? My car is out of the extended warranty. If these sensors are causing a safety problem, I would rather have them removed and replaced with a normal stem. Not sure why they put such a (apparently) expensive on lower priced car anyway.
You should also be aware that the batteries in each TPMS sensor will run down and, since they are not replaceable, the entire TPMS sensor will need to be replaced at some point (around 5-6 years based on my experience with a 2005 Mercedes).
Look at TireRack or one of the other alternative supplier - much less expensive than the smart dealers.
It does not make any sense to use pressure sensors. For the price of replacing the sensors, you can buy a really nice little air compressor (I did) and check your pressures once per week (I do). If you are going to drive a tiny vehicle like a Smart car, you should be intimately familiar with the most critical issue: tire pressure. Tire pressure sensors don't keep your tire pressures uniform, which is very important, they only tell you when the pressure falls below a threshold. For best mpg, you need max sidewall pressure. The sensors can't help you there. I can't believe how overpriced these useless gizmos are! The only thing worse is the people who think they are useful. Put quality stems on your tires and check your pressure. It only takes a minute per week. That's a lot less time than you have to work to pay for new sensors.
I had a rear tire suddenly lose pressure and TPMS light came on while in outer lane during heavy traffic rush hour on I 295 near Trenton here in Jersey about a Month ago. I was able to get over to shoulder rather than crash landing in the center grass median but smoked the tire in the process. I had not noticed previously but the TPMS sensors are all split through the valve stem as well as the nuts. I have seen a couple blog posts now about this. The Government mandated these supposed safety features in 2007. I believe they were just trying to improve EPA statistics but of course we are being sold on them as a safety feature by the manufacturers. Although I feel it was great to see the light so I could react to a potentially dangerous situation but it is especially disconcerting when the safety feature is actually the problem. I think we all need to make sure Mercedes is aware of these failures. My 2009 Smart had around 112,000 miles at the time this occurred. I think I will stick with regular old Schrader valve stems from here on out unless the infamous TPMS sensors at least come down in price. These were the original TPMS sensors on factory steel wheels. Now I am running the factory alloy wheels I had bought on ebay quite a while back but have used very little up until now because they did not come with the TPMS sensors and I did not like riding around with light on dash. Everybody wanted to hold onto those valuable sensors but the joke is on them once you run them a while the corrosion eats them up, I looked at the new cars on the Cherry Hill Mercedes lot and they seem to have changed the spacer and nut to a slightly different design that hopefully will hold up better. I did log my complaint with Smart and was able to get the dealer to document the condition of the others.