So, all four sensors report reasonable temperatures and "Battery Voltage OK", but LF is reporting the wrong pressure (by a wide margin).

I would like to "reset" that one sensor if possible, but I'm not seeing a simple way to do that. Lots of options to program a sensor and maybe have the car relearn the sensors ...

I might have to dive deeper into the whole TPMS thing ... :-)

 

You cannot reset or reprogram that sensor. It has failed and you need to replace it.

 

RacerRik: Yeah, looks like it. Have you experienced failed sensors?

 

I have come across many failed sensors, but never one that reported a low pressure like yours. All the ones I have seen that failed just quit reporting pressure at all. But you have proven with the TS508 that yours has experienced a unique failure mode. I don't know how much you work on cars / tires, but the TS508 is great if you do much work with these things. I have a tire changer and use it all the time, so the TPMS tool was a good investment for me.

I just changed four RE71R tires on a friends car this weekend. Those are one of the hardest tires to change. The sidewalls are unbelievably stiff! I invented new techniques and came up with unique tools to make changing high performance tires relatively easy. This is just fun for me. I bought the tire changer because I got tired of tire shops damaging my wheels and tires every time I had them do work for me. It will never pay for itself, but the satisfaction I get using it plus never having damage is worth it to me. The only problem is that I get a never ending list of friends and family that want me to change tires for them - and most expect me to do it for free. At least they owe me favors!

 

RacerRik: Thanks -- I have considered buying a tire changer, but sadly my little shop has no room in it. And then I'd have to buy a balancer, too. At least I have shop air.

Be happy I don't live near you, or I'd be dropping wheels and tires off 8-12 pcs at a time :-)

I now use a mobile guy who is really, really good.

 

Funny story - I originally bought a smaller tire changer and it worked great for the cars I needed it for. 9 months later, I bought my Corvette and sadly, the smaller tire changer could not handle the wide tires and wheels Corvettes use. So I ended up selling the first tire changer and bought a bigger one. I can now do wheels up to 24" diameter and 13" wide! Fortunately, the small tire changer was easy to sell and I ended up getting most of my money back on it.

Spin balancers are also huge machines. I did some research and found out that bubble balancers work just fine. Even though they can only do static balance and not dynamic balance, I found out the real reason all the tire shops use spin balancers is because the workers don't need a brain to use the spin balancer. So I bought an inexpensive bubble balancer and did some DIY upgrades to it. It works just great and I have had no issues with balancing all kinds of tires using a static only balance. You just have to use some smarts to figure out the best place to put weights on the wheels.

If you really do that many tires, having your own machine would probably pay for itself. Plus you can use it for trailer tires and breaking beads on small tractor tires. The foot print of even my "big" tire changer only takes the same space as a couple of trash barrels. And the bubble balancer is smaller than a 5 gallon pail.

You sound like a DIY type of person, so I bet you would love having these tools. If you ever decide to jump in, hit me up and I can give you lots of tips on what to buy and how to use the tools for perfect tire changes without risking damage to wheels or tires (or yourself!). To duplicate what I have would cost under $1500 and since you already have an air compressor you do not need to add that cost in.

The biggest problem with tire shops is they do not use the tools correctly. Now that I have my own tools, plus a few years of experience, I can see why tire shops damage so many tires and wheels. One of the biggest problems is that almost all tire shops use inside clamping when they change tires. They do this because outside clamping is harder and takes a bit more time. But the manuals for every tire changer say specifically you must use outside clamping for aluminum wheels. The shops flat out ignore the instructions of the tire machine manufacturers - and peoples wheels suffer the consequences.

The other major problem is not adjusting the drop bar height correctly. Again, this takes just a tiny bit more effort to do it right. The tire shops assume the plastic guards on the duck head will prevent wheel damage if the duck head rubs the surface of the wheel. This is untrue since dirty plastic rubbing against a painted wheel with huge forces the machine is capable of will certainly mess up the paint of the wheel if not scraping it off completely! They set the drop bar too low and the wheel rubs the duck head (because the inside clamp method allows the wheel to slip a bit) thus making a "touchless" machine into a tool that scrapes the lip of the wheel up. I found this out the hard way when I first started using my tire changer because I used it just like I saw tire shops using their machines. Fortunately, the few wheels I messed up were not my expensive Corvette wheels! I have not left a mark on any wheel since I improved my methods. I have a Mayflower changer which is a touchless tire changing machine.

Having this setup at home, I can do things like "flipping tires" to get even wear and prolong the life of my tires. I would never have considered "flipping tires" if I had to take them to a tire shop.

 

RacerRik:

As a tool freak, I envy your situation :-) If you can do that labor quickly and without much hassle (as it sounds you can, with the custom tools you created), then it's definitely a nice way to go.

Well, as much as I don't like to give up on solving technical issues, I agree that this sensor has simply gone bad (and has NOT had its battery die on me). Today, I deflated the tire (twice) down to 0psi, checked the TPMS reported pressure (0.0psi) with the scan tool, and pumped back up to 30psi, then 40psi and checked with my reference gauge and the TPMS reader. In both cases, the TPMS is reading around 15-20% low in this static, non-rolling condition. I read various threads about these TPMS sensors and (re-)calibration (not (re-)learning), including this one, and I see absolutely no evidence that it's possible to re-calibrate a sensor ... as-delivered factory calibration for life. So it'll have to be replaced. Only a few months after a new tire was mounted on a new wheel! :-(

To be slightly fair, these TPMSes came from my car's original track wheels, so maybe they've lived a harder life than usual.

For fun I scanned all my other vehicles' TPMS, and only one -- on the minivan -- reported anything other than battery 'OK'. So I'm of the opinion that you should rarely if ever see a TPMS failure within the first 10 years of ownership of non-tracked wheels. That's my opinion and I'm sticking to it!

BTW, do cars that come with spare tires have TPMS in the spare?

 

The only spare tires I see these days are space saver tires and they do not come with TPMS sensors since they run at higher pressures (60-80 psi) and are only intended to be used for 50 miles or less.

 

https://mechanicbase.com/tires/tire-...nsor-symptoms/