A New TPMS Saga & Question

A little over two years ago while fitting new tires I replaced the original wheel sensors in my 07 Boxster with ITM equivalents from OEWheels. Recently the RR sensor got 'lazy' and could not be read after starting the car, displaying (--). After about five miles the TPMS system would go 'inactive", then suddenly wake up after another five or six miles with all sensors reading normally. This would be repeated every time the car was re-started. Then one day none of the sensors would provide a reading from the start, apparently, and the system would go through a cycle of "learning", then "inactive". I called OEWheels to see if they had experienced this, and was told that it was possible that one sensor out of four could go bad after two years (BTW sorry your two-year warranty has expired), but very unlikely for all four... I should go to a tire dealer and have them scan the sensors before assuming they're all bad, as it might be a system failure. This made sense, and I took the car to the local branches of two well known tire distributors. Both shops used a Bartec TEC400 scanner, which seems to be the automotive repair industry standard, but after dialing in the make, model & year, neither could get a reading from any wheel… "so they must be bad, Sir!" The first shop just happened to have a set of the correct HUF sensors on the shelf and I asked to see them scanned for remaining battery life. They were hesitant, saying they had to be on the car and operating first, but opened one package to show me the sensor. I noticed clear evidence that it had already been mounted on a wheel, to which they admitted having mounting all four on another car by mistake, and having to take them off again. As far as they were concerned the sensors were like new, but still wouldn't scan them, and I declined. The second shop said sorry we can't seem to get a reading, but they're probably unique to Porsche and you need to go to your dealer… we would have to buy new sensors from them in any case if you wanted us to install them! At this point I realized I didn't know enough about these systems to diagnose my problem. I ordered a Durametric, Enthusiast version, and ran it for the first time today. The TPMS system came up with one fault indicating that the system was or had been inactive. I then checked remaining battery life for the sensors: two came up with 62 months remaining, one 61 months, and the original suspect (RR) zero! So my question for the more knowledgeable among us: is it normal for one completely dead sensor to result in the system defaulting to "inactive" rather than simply continuing to display (--)?

Seems unlikely that one bad sensor would cause the system to fail but I really don't have an answer. I'll follow the thread to see if anyone does. Wouldn't be the first time I'm surprised about how our cars work or don't work. But if no one does have an answer, I'd buy one sensor, have it installed and see what happens.:cheers:

I'm not 100% positive but my understanding is one bad sensor results in system failure.

i keep telling people this all the time.. but they wont listen.. 5 years vs 2 years.. twice vs. once.. is it worth it? Lemon

Yes, only takes one bad sensor for the entire TPMS to read as inactive. I had a similar situation in that one sensor's battery was dead before the other three per Durametric. All was well after installing a new set all around.

When the first senor died on my '08 CS the system continue to function, but as soon as the second one died the it started a cyclic pattern similar to that described. Now with 3 dead I see the one wheel reading for the first few miles after startup and then system inactivates.

Mine did that. One wheel came up -- and shortly thereafter went into the learning/inactive loop. Got around to checking with Durametric and shows one dead and the other with varying amounts of like left. This feature struck me as odd also. I would have expected it to read the working ones and show the other as --. There should be a fault message but doesn't seem right to have the whole system go belly up.

My thanks to everyone for the input. Confirms my thinking that the system is OK, just one totally dead sensor turning it off. Have ordered a full set of HUF OEM sensors to hopefully be done with it, rather than just change the bad one and face the possibility of the remaining ITM's also failing prematurely. Will post the outcome when they've been installed.

Has anyone had any luck with the Schrader TPMS sensors . My mechanic tells me they have a set that is programmable for my 07 Boxster ?

There is nothing special about the TPMS in the Porsche , it's just a 433MHZ sensor. The Schrader is programmable and you can get them for about $24. It has rubber stem instead of metal. If you don't mind the rubber stem and can have them install for cheap then I don't see why not.

Q, thank you for the confirmation, literally $ 800 CDN cheaper than my Indy wanted and even a larger savings over what the dealer quoted. More money for the stereo upgrade

Sorry I don't quite understand, and you solution is?

people tend to get chinese aftermarket TPMS ...Sometimes they get lucky and a lot of times they don't.. They end up spending twice.. to get the proper hufs later.. Each time a tire shop takes out your wheels and physically goes to your chinese TPMS it cost 80 dollars.. is it worth it ? Lemon

I agree with your point completely! No only that but all of that wear and tear on the tires and wheels! I wonder what kind I got with the winter tires set I bought from Tire Rack ...

I have to ask but why do these things even have batteries, or at least not re-chargeable batteries? Your wheel is constantly rotating, it would be easy to have a sensor with a little mini generator in it to generate enough current while in motion to operate the TPMS sensor and enough capacitor or battery reserve for when the car is sitting. It would, much like an alternator /generator keep the battery in the TPMS sensor charged virtually forever. To put a static battery that simply runs down over time and is hard or expensive to swap out seems like just a ploy to sell more TPMS units to me. If I were an electronics engineer (and not just playing one on the internet) I would whip up a circuit/device for this and go get a patent then sell them in the aftermarket as LIFETIME TPMS units.

You're not the only one to wonder this. Just having a rotational sensor to switch the things off after stopping for a while would extend the life significantly. If I remember the requirement it's showing a 25% pressure loss in 20 minutes. Nothing about being able to check your tire pressures without starting the car. The other one I wondered about is if the sensors could be powered by the receiving antenna like the RFID tags. Those don't take much power but it is possible to transmit more. With how long the things go on a battery they don't use much. Then I still can't help but wonder why they didn't leave well enough alone and continue using the ABS wheel sensors. If all you have to flag is a 25% loss in 20 min that would seem to cover it. There's just something about spending $400 for sensors ever few years because people couldn't be bothered to use a $20 tire gauge just irks me.

Just an update, yesterday I had the Schrader TP sensors installed, everything is working perfectly and the final cost, tax in was $ 387.00 CDN, I saved over $ 800.

Were these installed because the original batteries were failing or is this a different set of wheels?

Original batteries had died.

That is a bummer and a very expensive set of batteries!

At least it was a lot cheaper than the dealer or Indy options. I was a little hesitant trying them, but in the end they work perfectly and the extra $800 is going toward the new stereo/Nav head end that is going in later this week I see you have an new GTS coming in, what color did you order?

Glad the TMPS swap went well! I had a tough time deciding on the colour, I would have really liked to do a PTS, but between the added expense and the delay it would have introduced I decided to stay with stock colours, in this case Dark Blue Metallic. If I ever get to do this all again one day I hope to plan much further ahead and try something different, I am sure this would cause even more consternation!

LOL, my co-worker has a GT-4 on order and colour was his toughest choice as well, funny enough he chose the same colour as you. My 987 is Midnight Blue Metallic, which looks very similar (at least on line). I love the colour, Like Black but with a bit of pizzazz! I look forward to seeing some pics.

OP here… sorry, I've been out of the loop for a couple of weeks, but just had a new set of HUF RDE001 sensors installed, and everything is back to normal at last. This confirms again that one dead sensor will cause the TPMS system to totally deactivate. I dissected the known bad ITM sensor and was surprised to find the battery was actually OK, measuring 3.05V (they are designed to be 3V nominal when new). This suggests that the associated electronics failed instead, most likely the RF transmitter since my Durametric revealed no data at all from this particular sensor. I expected to see a cheap no-name battery installed, but was pleasantly surprised to find them using Swiss-made Renata batteries: CR2450N Li-ion. Out of further curiosity I went on to dissect one of the working ITM sensors and it's battery measured 2.84V. Getting the new HUF sensors and having them installed turned into a saga of it's own! Site sponsor Schnell Autosports had them on backorder and I got them from ShopTPMS - We are the largest supplier of OE TPMS sensors service packs and diagnostic tools. Tire Pressure Monitoring System (TPMS) is an important safety feature and we are dedicated to selling the best products on the market. Wholesale and retail instead. A good price, but they sent the wrong valve stems, 11mm dia. instead of the 10mm required for my OEM wheels. The tire shop was able to swap them for the correct size. However, an over-zealous tire jockey started to break the bead of the first tire before all the air was out and split the sidewall. Naturally they didn't have my size Michelin Sport PS2 N1 tires in stock, and this was a Friday. They put a temporary Kumho all-season tire of the correct size on so that I could drive home. It took four days to get two new tires in… one to replace the destroyed tire, plus another for the other side since I wasn't going to drive on a pair of uneven tires. Other observations: I noted that the tire shop was not using torque drivers to install the sensors, and was told no-one does that, "we just use common sense". A grandson of mine that works at a Miata dealership confirmed that this was the norm there too. He added that this would soon be a thing of the past anyway since Mazda, at least, were now using wheel speed to detect abnormal pressure. As previously reported, two different tire shops failed to see any signs of life from my working sensors, each using a popular Bartech RF scanner. Makes me wonder if anyone in the tire and auto service industry really know what they're doing with TPMS!

What a nightmare install. I'd never return to a tire shop like that again. I use my indy for installing and road force balancing my Tire Rack tires and installing TPMS which I supply. He is a recommended Tire Rack installer and actually will take the time to point out flaws in the finish of the wheels before working on the wheels, just so he doesn't get blamed for some existing finish flaw or damage. It's one of the things I worry about most with my plan to move to Florida full time in about 6 months. I'll have him service the car one last time before I drive it 1200 miles again but this time the car will stay in Florida instead of coming North in the spring like it's done for the past 3 years. Then I have to start a serious search for a new Florida indy that measures up to my current one's very high standards.:cheers:

Sorry to hear about all your problems with something that should be so minor. Lets hope all the bad Karma was used on this incident and the yu have smooth sailing (driving) from here on.

Another possible source would be FCPEuro ? They have sensors and their warranty is great, so even if something goes wrong I imagine they'd help? I asked them some questions about shocks on my wife's Jetta, and they were supremely helpful even before the sale.

I have bought other Porsche related parts from them, great company but I don't see that they have HUF TPMS units for a 718 only Autel units that take rubber valve stems. Porsche 718 Spyder Parts | FCP Euro You would have to search for your specific application or call to be sure.

Interesting. They have HUF TPMS for my 987.2 , so I assumed they'd have it for your 987.1 ... but then I see a 718 is mentioned (OP was talking about 987.1 ... and this section of the forum is for 987, so I'm a bit confused. Maybe I missed something along the way...