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Discussion Starter · #1 ·
I test drove a Rav4 last week. The TPMS warning light came on while driving. A check at the next gas station revealed that all 4 tires were about 10% over pressure, can that also cause an the warning to come on? It was a hot day.

In this 2015 model, is it possible to see which tire is low on pressure, or is a fault code reader necessary for that?

Because no 1 tire was referred to by the warning light, perhaps it was a general warning that indicated an issue with the system. I know that in places where folk change their wheels twice a year, it can be an issue re-programming the wheels to each corner of the car.

Personally I don't need the sensors because I check my pressures regularly, however it must be functioning to pass the local tests/inspection.
 

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@Jack Daniels

This thread, TPMS Initialization, gives a good explanation of how the TPMS system works on the RAV4. The RAV4 does not have the means to identify which tire it believes is low, and the system is designed to set the alarm only when pressure drops. TPMS information is not accessable through the OBD2 port with a code reader, at least with the two that I have. A dealer or independent garage with Techstream would probably be needed to access TPMS data.

Since you measured the tires at over the normal pressure, it would lead me to believe that there is a fault in the TPMS system on the car you were driving (most likely) or that the initialization pressure on that particular car was set so high that 10% over pressure would set the alarm as being 25% under inflated (not likely).

My best guess is that one (or more) of the wheel sensors was not sending a signal to the car, so it set the alarm and lit the light. This is probably not unusual for a six year old car since the wheel sensors are powered by batteries.
 

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Discussion Starter · #3 ·
Thanks for the good explanation, the tires have all been replaced today at a Toyota dealer, so I guess they will have replaced at least 1 or perhaps all 4 sensors.

Is it common practice to replace all 4 sensors when 4 new tyres art installed?

I'll test the alarm set point by letting some air out, and re initialize if it's not correct.
 

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Is it common practice to replace all 4 sensors when 4 new tyres art installed?
I would say this is not a common practice. These are most assuredly something that the dealer will want to charge you for, either replacing the battery or a faulty unit, so if it is not noted on the invoice, then I would feel confident that they were not replaced.

So it sounds like you purchased the car after the test drive, has the TPMS light continued to be an issue since then?
 

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Thanks for the good explanation, the tires have all been replaced today at a Toyota dealer, so I guess they will have replaced at least 1 or perhaps all 4 sensors.
No way unless all were not functioning properly. It is an expense that they have no desire to incur unless something is wrong/broken.
 

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It's unfortunate that Toyota went with the basic TPMS information system, because TechStream does in fact display the psi from each wheel - they just don't do anything with it but trigger a global alert, requiring you to check each wheel. Do note however that a sensor failing to communicate will cause the TPMS light to flash (indicating system trouble), as opposed to on solid which indicates low pressure.

As for replacing all 4 sensors, I can envision this being suggested for older vehicles because it would be cheaper to replace failing batteries all at once rather than one at a time as they fail... But that would depend on age...

Edit - I believe the average life of TPMS sensor batteries is around 6 years, but I just traded my '09 Honda CRV in for my Rav4 and the original sensors were still working fine...
 

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Everytime I read about problems or replacing TPMS sensors, I am glad it's not law in Canada to have them & my Canadian built Rav4 does not have them.
 

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Everytime I read about problems or replacing TPMS sensors, I am glad it's not law in Canada to have them & my Canadian built Rav4 does not have them.
Yeah, it's a double edged sword... A great idea but lacking standards and costly to implement. Seems like it would be pretty easy in this day and age to have generic sensors that the car could register willy nilly, so when you changed wheels it just updated itself automatically. And if you're going to implement it at least take advantage of the technology you're using and let the driver know the pressure in each wheel so you know which one to check when the light comes on - that should be standard, not a special option!

Worst of all, many manufacturers disable stability control or AWD features if the system detects trouble... I could see a driver needing stability control more than ever if a tire goes flat...
 

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Discussion Starter · #9 ·
So it sounds like you purchased the car after the test drive, has the TPMS light continued to be an issue since then?
Yes I did buy the car and picked it up yesterday with the warning light still illuminating occasionally. It is both solid at times and flashes occasionally, half the time it's not visible. The car has a 6 month guarantee so the dealer will have to replace the sensors or batteries regardless. I'm surprised that they didn't replace the batteries as a precaution during the new tire fitting.
the average life of TPMS sensor batteries is around 6 years
The car has just turned 6 years old. A set of winter wheels were included, is there any way to test those before I fit them to the car? ...to avoid just having to take them off again straight away for battery replacement.
 

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Yes I did buy the car and picked it up yesterday with the warning light still illuminating occasionally. It is both solid at times and flashes occasionally, half the time it's not visible. The car has a 6 month guarantee so the dealer will have to replace the sensors or batteries regardless. I'm surprised that they didn't replace the batteries as a precaution during the new tire fitting.

The car has just turned 6 years old. A set of winter wheels were included, is there any way to test those before I fit them to the car? ...to avoid just having to take them off again straight away for battery replacement.
Like RTexasF pointed out, it doesn't surprise me that they weren't replaced at the tire change as it would have cost the dealer money. I am sure dealers in your part of the world aren't different in that regard than the ones stateside...:)

Since you do have a 6 month guarantee, it would be worth your time to take it back and have them address the issue, especially since there is an off chance that it may not just be a sensor. Either way, try to have them stand behind their guarantee.

Regarding the winter tires, I would just swap them on and take them for a drive and see what happens. If the TPMS light goes out then you know that the winter tires sensors are good and that the likely culprit is a sensor on your summer tires. If the light stays on or flashes, then take the winter tires to the dealer when you go for the summer tires and try to have them replace those at the time as well.
 

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is there any way to test those before I fit them to the car?
They do make scan tools that can check sensors in uninstalled tires, but you probably don't want to buy anything. As kensei mentioned, you could swap the tires and just see what happens, but I also think many tire stores would be willing to check them for a minimal fee (if not free).
 

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Discussion Starter · #12 ·
The dealer will be sorting it out so I wont be doing anything about it myself. I can ask if they have the pressure sensor scan tool. If so Then I can return the car with all 8 wheels to be scanned as fixed as required.
The winter wheels wont be installed prior to probably november.

I have a scan tool myself, an OBD reader, not a TPMS sensor scanner, I guess I could try that to see if it displays a system fault code or just a pressure sensor.
 

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Just as an aside, up in VT we run winter sets as well... I was looking into setting up a TechStream laptop to manage the TPMS swap but just played around with a free trial of the Carista app and am VERY impressed - it works fine with my BAFX OBD2 adapter and in addition to std error code reading it can set numerous custom options (seat belt buzzers, auto high-beams, etc) and also can register TPMS sensors (though you will need to know their ID codes to type in)... The whole thing was stupid easy to use (not to mention virus free - try that with the cheap TechStream hacks!) and they offer a free 1 week trial. Come winter, if I can't get the TPMS sensors reset for free, I'll do it myself with the Carista app.
 
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