TPMS sensor - which one is bad?

If you were to get the mini VCI cable (eBay) you could see the individual tire pressures and determine which one is acting up. You could also program the new sensor.

 

What about the spare tire? Does the spare have the sensor as well?

 

Go to NTB or Discount Tire and they can isolate which one it is. Then it's your call how to handle it.

 

No, the spare doesn't have the TPMS sensor.

 

I just replaced 3 sensors on my 2006. The battery on the first one died, and I had it replaced with one of the $30 ones. About a month later, I replaced another 2 tires (worn out), and replaced the sensors at the same time. I'll wait for the last one to actually fail, but I assume that will be soon.

Techstream identifies the sensors as ID1, ID2, ID3, and ID4. The way I matched up the ids with the tires is I dropped the pressure in one tire, and looked at the Techstream tire pressure report to see which one it was. Supposedly ID1 is left front, ID2 is right front, ID3 is right rear, and ID4 is left rear. Mine were nothing like that. I checked my wife's CT200h which has had the tires rotated once, and the pattern was flipped left to right. Sure hope they didn't rotate them side to side...

The alarm values were not set on the CT200h. Apparently the reset button had never been used. I assume that that means that there would never be a warning. Hey, for all the hassle, the least they could do is activate them! I pressed the reset, and the alarm pressures showed up on Techstream.

One of the 3 new sensors on the Prius reads about a pound high with Techstream. And another one of the 4 on the CT200h reads a pound high. I set all of the pressures with the same gauge, and 2 of the 7 sensors read high.

 

Confirming Toyota Techstream will tell you which tire has a bad TPMS sensor? Also wondering what kind of battery they use?

 

Techstream will tell you which ID slot (ID1, ID2, ID3, or ID4) isn't receiving the sensor signal. And on the same Techstream data list page, you can see the sensor ID number that is registered in each slot.

And with that, if your X-ray vision is good enough to see through about ½ inch of rubber, you can read off the ID numbers printed on the sensors inside each of your four tires, and match 'em up, and then you know which one went bad.

But it's even easier to look at the pressure readings on the data list page, and go around the car letting a few pounds off one tire at a time, and see which readings go down (and which one doesn't).

And even easier than that is to go to a tire place that has the kind of radio wand they can just wave over your four tires and say "yup, it's this one here".

There is a thread or post around here somewhere from not so long ago where someone really, no fooling, did replace the battery in one of the sensors. Took the sensor out, opened it up, excavated down through all the solid silicone potting, dug out and unsoldered the battery, soldered a new one in, repotted the whole thing with new silicone and somehow reassembled it.

The details of the battery can probably be found in that post. It did show dedication, for sure.

 

Ok... Letting air pressure out sounds easier than my first thought of taking a wheel off and carrying it to the other side of my garden so it's out of range.

And sounds like from what you're saying these sensors aren't designed to have their battery replaced and you just buy a new one?

That's funny how all the Cosco tire stores try to sell you a TPMS "maintenance" service which they once told replaced all the gaskets and tested it, which I assumed meant a new battery too, but I guess not? Lol, there's so many way shops sell extra automotive services that aren't actually of much substance.

 

They are soooo not designed to be serviced. The battery may be chemically a typical coin type lithium, but it has little metal tabs spot welded onto it, and those are in turn spot welded onto the TPMS device. All of this is buried in silicone potting. I watched a video of a guy replacing a TPMS battery, and it was a big PITA and I wasn't convinced that his soldering of the tabs to the TPMS, instead of spot welding them, would hold up for very long.

I vaguely recall a post in one of the Gen 2 forums about some TPMS sensors at a reasonable price which can be bought on Amazon or Ebay which are compatible with this Prius. Seems like a safer choice, since if one has failed, odds are, others may not be far behind.

One of my sensors is out and I just ignore the warning light, while checking the tire pressures every month or so. I think when the dealer put new tires on this car before selling it (I bought it used from a Toyota dealer) they cheaped out and didn't replace the TPMS sensors.

 

Yeah... I haven't bought tires in many years and I was far less DIY back then. The bit of information that led me to believe they were serviceable was because back in 2014 Costco tried to sell me a "TPMS service kit" and claimed they replace all the washers and seals and caps and other parts for like $5 per wheel. I declined, but assumed this meant TPMS were serviceable and if something was serviceable I thought that meant you could change the batteries, but I was wrong. They were just selling overpriced valve caps and spacers that probably weren't needed in the first place. Lol...

 

To change the battery, you have to remove the sensor from the inside tire. Any tire shop would install a new TPMS for ~$50 per tire. This includes 1.dismounting tire, 2.replacing TPMS, 3.remounting, 4.balancing and 5.relearning TPMS if necessary.

With my own Autel TS508 TPMS tool, I can do step 5 myself. Autel TPMS sensors are $30 each online, but I got 8 sensors in a kit with the tool. The cost was just $18 per tire which is the same as installation of a tire.

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Yeah, I'm gonna go even cheaper than that. As in I found one on Ebay for $15 and plan to buy it and measure its weight. Then take the wheel to the tire store and have them swap it out with the bad one for $10 and then measure the weight of the old one and if they aren't the exact same weight I'll pay them an additional $10 to re-balance the tire.

 

But even if the weight is close enough, if the shop dismount the tire from the rim to replace the sensor, then you would in theory need to balance the tire.

I have seen a YouTube video where a DIYer broke the bead and separated it from the rim just enough to stick a tool to remove the old sensor and valve and replace it with a new one. Then re-inflated the tire. This avoids the need to balance if the sensors are close in weight. But I doubt a tire shop would do that normally.

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That's a great point... And it'd be way less hassle to fix these for myself and others if I used my super long pry bar. Of course, maybe I'll do some research and see what it would cost to get a good price on a tool that's designed for the job so I don't do any damage? Any suggestions?

And thanks so much for nudging back towards DIY! It's so frustrating to have to pay someone else to do car work for me and you just helped me realize this is possible!

 

Search YouTube for "TPMS replacing", you will find plenty of methods, most of which using a minimal tools.

For example:

I thought about trying on my own winter tires, but I had to do all 4. And in my experience, even with a professional job, I have often had a slow leak from a bad seal in beads or valves soon after a tire change at a shop. I did not want to deal with the issue just for saving $18/tire. So I just waited long enough till I needed to put on new tires, and had a shop install TPMS I cloned off the summer tires with working TPMS. So, there was really no extra cost.

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They're all near the end of battery life. Replace em all. Make the car reliable

 

I don't know which one you want fom ebay, BUT...most "universal" TPMS sensors need to be programmed in order to work for a specific make - model- year range of car.

Buy a sensor from a Toyota dealer for a Gen2, and you can copy down the ID number (to write it to the car's ecu via TechStream), then install the sensor on the wheel. Good to go.

A universal sensor needs to be "told" what frequency it works on, and that you're putting it on a Gen2 Prius. Also need to decide if the programmer tool should generate a random ID, or if you are "cloning" the existing ID. Also the tool can "ping" the sensor to confirm it works, and check status on the other sensors.

Cheap can work, but it ain't always the least expensive route in the long run.


FYI, as mentioned, TPMS batteries are effectively sealed in the sensor- dead battery = new sensor. TPMS "service" usually denotes removing the sensor and replacing the valve stem (if separate) and seals. Metal stem design like on Toyotas cause lots of corrosion leaks in the salt belt and are a pain to deal with.

Also, if you need to change the TPMS ID's with TechStream, I don't recall if you can just do one sensor, or if you have to rewrite all four at the same time. So you might want to record all the current ID's before doing anything.

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Yes. The good news is you can see all the currently-registered IDs in Techstream. So you can just write those down before you start the registration process. There you have to enter all four IDs, so you just enter the new one(s) and re-enter any that you're reusing.