TPMS electronics - Page 1
Forum section: electronics / projects

author: Peabody
author_rank: Super Contributor
timestamp: May 17, 2023, 05:26:04 pm
content: I have a Honda Civic that will be 12 years old next month, and the original battery-powered TPMS sensors still work, which I don't quite understand. I'm told a new sensor has to be woken up after installing it in the wheel. That's to maximize the shelf life of the part after manufacture. I also understand that the sensor won't detect low pressure unless the car is moving at about 25mph or more. If that's the case, any transmissions might be disabled unless the car is underway. That might explain why mine have lasted so long - because it has very low mileage.But I need new tires, and my main question is whether the various aftermarket sensor replacements would have similar designs that would give them long life. I see reviews for some of them on Amazon that indicate otherwise. I suppose I could use genuine Honda parts if that's what's needed to get 12 years on the new ones.Anyone have experience or knowledge on this subject?

author: ejeffrey
author_rank: Super Contributor
timestamp: May 17, 2023, 05:42:44 pm
content: I think all TPMS transmitters work mostly the same way -- only waking up when the vehicle is moving, but I have no idea if the aftermarket ones have shorter lifetime than OEM -- It likely depends on the specific part, with almost no reliable way to determine what you are getting.

author: Benta
author_rank: Super Contributor
timestamp: May 17, 2023, 06:24:28 pm
content: Are you certain your car has an active TPMS?Your remark about it only working above 25 mph makes me suspect that it's a passive system.

author: nali
author_rank: Frequent Contributor
timestamp: May 17, 2023, 06:48:53 pm
content: American models may be different but I'm pretty sure my Civic uses a passive system by monitoring each wheel speed or travel. Needs to be manually reset if tyres are inflated or changed.https://tridenthonda.co.uk/downloads/honda-deflation-system-warning-user-guide.pdfQuote

author: Peabody
author_rank: Super Contributor
timestamp: May 17, 2023, 09:16:29 pm
content: 2008 - 2014 Civics used an active TPMS, with battery-powered sensors. Beginning in 2015, an inactive system was used. So yes, I'm sure I have active sensors.

author: nali
author_rank: Frequent Contributor
timestamp: May 18, 2023, 07:09:23 am
content: Quote from: Peabody on May 17, 2023, 09:16:29 pmMust be market differences then. Mine is 2012 (Mk9) and has the Deflation Warning System. In fact at the moment that car has a dodgy wheel speed sensor which causes the DWS to error (it's not an uncommon fault on this model).

author: electrolust
author_rank: Unknown
timestamp: May 21, 2023, 12:18:38 am
content: Quote from: Peabody on May 17, 2023, 05:26:04 pmYes, the preferred design for TPMS sensors is that they require the car to be in motion. Many of them can also react to an RF signal from a probe tool. I'm not sure how that works while maintain shelf life. I guess that part of the circuit is either ultra low power or can extract enough power from the RF itself, like RFID.Given that amazon is largely a western UI for aliexpress these days, you can't trust any sensor you buy there. You also can't trust any sensor you'd get installed at a tire shop. If you want to guarantee the longevity you'll have to buy from Honda. If you expect to keep the car another 12 years, the addtional cost is likely easy to justify over 12 years of amortized expense.

author: Peabody
author_rank: Super Contributor
timestamp: May 21, 2023, 02:07:31 pm
content: It turns out there are a number of Honda dealers who have discount online parts businesses. The Honda forums report that these dealers do sell genuine Honda parts, and at a significant discount. So I picked one they recommended, and have ordered the sensors for about $35 each including shipping. The cost at my local dealer would have been $52. But the most expensive would have been at the tire shop, which would charge me $60 each for Dill sensors. Oddly, the tire shop says there will be no charge to install my sensors as part of the tire change.The cost at Amazon for what they claim to be genuine Honda sensors is $39. It's just not clear from the reviews that they are Honda parts, or who exactly the seller is.Of course there's no guarantee that the OEM sensors will last as long as the original sensors. But you just have to make the best decision you can, and hope for the best.