# Can a TPMS sensor cause a tire leak?



## NickD (Dec 10, 2011)

Not really an expert on these things, but as far as I can see, its just hanging on the valve stem. See a variety of valve stems, really don't know if these are all standard.

Can wonder why its even mounted on the valve stem where centrifugal force is the greatest with a possibility of it shaken loose. Could be mounted on the inside of the rim using the good old fashion cheap conventional Scharder Valve stem that has successful 100 year old history. And held in with a couple of screws.

Looking at various hardware seems like a couple of bucks new valve stem would be the cause of a leak. But not according to my son's dealer, hit him with an 80 buck bill to replace it.

Also understand some use a battery that can go dead when technology exists to make these sensors passive and cheap technology at that!

Just appears to be another means for the consumer to be robbed and not in a dark alley with a gun pointed at your head. And not a very intelligent design.

You want problems? We have problems.


----------



## Robby (Mar 1, 2013)

The Cruze (and most others) utilize a standard (appearing to the outside) valve stem.
On the inside of the wheel side, the stem has a female threaded shank about 1/4" long in line with the center of the stem.
To this, the TPM is attached.....it slides on to the shank, which has a flat so the sensor can't turn independent of the valve, and is held to the valve using a T-10 headed torx screw.
In this way, the moniter is in the wheel tire chamber, but cannot contribute to any leakage.
As far as the stem/valve assembly......same as always.....the schrader can develop a leak or the stem can leak between itself and the stem bore of the wheel.......this happens often with alloy wheels.
The bore grows corrosion at the interface and then leaks.....real slow, real aggravating.

Repair is, dismount tire (for ease of access) remove TPM from valve stem, remove stem from rim and clean the bore with a rolled bit of scotchbrite.
I install a new valve with a light coating of rim sealant to arrest any further corrosion, and then re-attach the moniter, remount and balance.

You lucky folks that don't deal with road salt likely will never see this type failure......seems to snow belt only.

Rob


----------



## NickD (Dec 10, 2011)

So you are saying the sensor itself cannot be the cause of the leak. Valve stem leaks are as old as road salt itself. Like to clean these as you do with even a tad of anti-seize inside of that hole.

Would think a bad sensor would show a very erroneous reading on the DIC. As a matter of fact, this vehicle is his wife's daily driver, the alarm went off to warn her a tire was low as the very first sign of a problem. So apparently the sensor is still working and showing the correct pressure now. Son did tell me after the car was returned, checked all four tires, two were reading at 45 psi, other two in the 30's. After putting in the correct pressures in all four, with a good gauge DIC matched the tire pressure.

But was with the new 80 buck sensor, have to tell him his dealer saw him coming.


----------



## Robby (Mar 1, 2013)

If the vehicle has a info center that shows each tire position, a bad sensor will show --- three or four dashes with no numerals.
If a GM vehicle, it will also say 'Service TPM System'.

Like anything electronic, they fail sometimes.
Speculation abounds......but consider the horrible environment these things operate in........bump/bang/crash/cold/hot....I'm surprised thay go longer than a month.

Yes, they have some sort of battery....must be a good one....07 was the first year they were required and I am not seeing a high rate of failure due to age.....'yet'
As I understand it though, the sensor goes to 'sleep' and only transmits if the transciever calls for a report or there is a rapid variation in pressure.

As a repairman, there is enouph to consider when something isn't working as designed......I try to limit my brain damage by not getting too deep in the design end......although....like this subject, I admit to digging deeper than I needed to....guess I found the concept intriging enouph.

Being a bit nosey though, what vehicle was your son driving that needed this service?

Rob


----------



## obermd (Mar 3, 2012)

Discount Tire recommends replacing the TPMS sensor when you replace tires. Two reasons for this - corrosion and battery life.


----------



## Robby (Mar 1, 2013)

obermd said:


> Discount Tire recommends replacing the TPMS sensor when you replace tires. Two reasons for this - corrosion and battery life.


Of course they do.......and if I owned a franchise like that I would make the same recommendation......reason one is to cover my tail.....I don't want to see a whiney customer a year after he buys tires.....reason two....I am income motivated, and so are they.

Rob


----------



## neile300c (Jul 8, 2014)

all TPMS have service packs, they are recommended to be changed when changing tires. I have had 3 cars come in the last month that had a slow leak by the valve stem, guess what fixed it ..... a new service pack. Yes it can leak there.


----------



## JerTM (Dec 12, 2014)

$80? You can EASILY replace just the valve stem without the sensor, sounds like your boy got ripped off.


----------



## revjpeterson (Oct 2, 2013)

The sensor itself doesn't cause any leakage, as mentioned above. However, some of the designs that were implemented to make use of these sensors did cause significant leakage problems. Many of the early TPMS systems used an aluminum valve stem instead of rubber. Between road salt and extremely hot or cold conditions, these frequently resulted in air loss from the tire. 

I've been fighting this with my wife's 2005 Town & Country for several years and 3 sets of tires now. Either the O ring that seals between the valve stem and the aluminum wheel fails or the core kit inside of the valve stem fails, causing a slow leak. My tire guy tells me that all of these aluminum valve stem designs have this problem, but designs with the rubber valve stem (like our Cruze) and TPMS don't seem to be a problem. Right now, I've got one tire on that van that has no damage, has been re-mounted to make sure the bead seal is good, and has had the valve stem/TPMS unit remounted and the core rebuilt, but it still drops enough pressure to light the TPMS warning (about every 3 months in the summer, about every 2 weeks in the winter, and every time the temperature drops more than 40 degrees in 24 hours). I just keep topping off that tire every time my wife tells me the light is on until next time I get tires (if there is a next time - it's at 150,000 with 40,000 of life left in the tires) and see if we can find another fix.


----------



## NickD (Dec 10, 2011)

> Being a bit nosey though, what vehicle was your son driving that needed this service?
> 
> Rob


It's a 2010 Dodge Nitro with only 18K miles on it, purchased it new. It was degraded to a daily driver last summer, probably not accustomed to road salt yet. 

Miss my old neighbor, had both a tire changer and balancer in his garage, was always a DIY job. Was thinking about getting one for myself, but need more space. See rockauto.com only charges 32 bucks for a complete replacement sensor assembly. 

As far as I am concerned, more junk to go wrong, always check my tire pressures. And just to have this "convenience of checking them on the dash is not worth the huge extra amount of money they charge for these things. Besides this, only a check, where is a guy suppose to get some air?


----------



## brian v (Dec 25, 2011)

For $ 20.00 any some one can get air from Walmart , K Mart , Target . Sears .. Pep Boys . 00,50 cents at specific Filling stations and those are a select few ............


----------



## jblackburn (Apr 14, 2012)

brian v said:


> For $ 20.00 any some one can get air from Walmart , K Mart , Target . Sears .. Pep Boys . 00,50 cents at specific Filling stations and those are a select few ............


My little cigarette lighter Craftsman air pump has been a fantastic use of money once the weather got cold. 

A full-blown air compressor with a tank is always a good investment for a garage, if you have one.


----------



## Sunline Fan (Jul 29, 2012)

jblackburn said:


> My little cigarette lighter Craftsman air pump has been a fantastic use of money once the weather got cold.


So is a non-plug in/breathing type of blow job, -J.



Sent from my awesome iPhone


----------



## Robby (Mar 1, 2013)

NickD said:


> It's a 2010 Dodge Nitro with only 18K miles on it, purchased it new. It was degraded to a daily driver last summer, probably not accustomed to road salt yet.
> 
> Miss my old neighbor, had both a tire changer and balancer in his garage, was always a DIY job. Was thinking about getting one for myself, but need more space. See rockauto.com only charges 32 bucks for a complete replacement sensor assembly.
> 
> As far as I am concerned, more junk to go wrong, always check my tire pressures. And just to have this "convenience of checking them on the dash is not worth the huge extra amount of money they charge for these things. Besides this, only a check, where is a guy suppose to get some air?


Ah, yes......a late model Dodge.
It has those nasty (and expensive) aluminum things that are mentioned above your post in the posters van.

Now THOSE can cause a leak......as noted many start to leak at the threaded barrel/'O' ring/ stem bore........another earlier poster mentioned a reconditioning kit.
Those kits are specific to the Mopar design.....a new nut, 'O' ring, and backup washer.
Trouble with that design is in the snow belt the salt wreaks havoc with the threaded barrel........it will often snap off and then you cannot add air to the tire (if it snaps above the schrader)......worst is when it takes the schrader with it.....instant flat, no joy at all.

If you look at Rock Auto's listings you can convert to the newer and less problematic rubber design similar to that found in the Cruze.

Rob


----------



## NickD (Dec 10, 2011)

Noted that my Cruze has that rubber valve stem. So what you are saying my kid can expect to lay out another 240 bucks if he goes the same route as the first one.

Was telling him, I use to pop the bead on a tire to change just the valve stem by using a bumper jack with the base of it angled and at the edge of the rim. By attempting to jack up my old motorhome. Have a motorhome yet, but no more bumper jacks. 

Didn't pop the other side, didn't have to, could cut off the old stem, and still have that cord with a handle on it, with a female thread that screws unto where the cap screws unto. Was quicker than driving to town. 

Purchased a real two HP air compressor back in 1965, still have it, still works, Made in the USA, but had to replace the belt about two years ago. Stretched so couldn't adjust it anymore.

Ha, when we first moved here word got around I have an air compressor, so every kid in our block came over to get their bike tires filled. Think a couple even moved in, had so many kids, couldn't keep count. Also have two Coleman portable air compressors, cigar lighter type. Can output as much as a 150 psi, but they teach you patience. Also nice for an air mattress when camping.


----------



## Robby (Mar 1, 2013)

Nick,
If your boy is operating in the salt belt, based on all I've read and seen, they will corrode and leak.

This is critical to their longetivity.......only use plastic valve caps and never leave them capless.
Any metallic cap sets off rapid electrolisis......sometimes the metallic cap will be welded to the barrel within a month.

Operated capless, the salt works down into the barrel and corrodes the steel scrader valve nut to the inside of the barrel.

As they fail.....and they will...convert them, one by one to the rubber type.
Wheel transmitters are the same frequency on Mopar (and many others......315 mhz.)

Rob


----------



## NickD (Dec 10, 2011)

Gave this information to my kid, first reply was, are you telling me I was ripped off? Just said no, buy trying to save you from getting ripped off from another 240 bucks.

Did find replacement rubber valve stems completer for his vehicle for a buck fifty each. And the only reason to replace the sensor was if it quit working. But yours was working, told you the tire pressure was low. 

Thanks for the information Robby. Nice to have a knowledgeable board member.


----------



## NickD (Dec 10, 2011)

Been shopping around just for the tire valves at several of my local suppliers. Coming up with zero, a tire shops, want to sell the entire assembly with the sensor. Claim it also goes bad, but that tire sensor told the tire was low in the first place.

Guess the only way to buy just the tire valve is off of the net. Ha, if it wasn't for the net, would have gotten rid of my Supra a long time ago.


----------



## Robby (Mar 1, 2013)

Nick, your Chevy dealer should have them in stock.....they come with a new torx screw to attach the TPM to the new valve.

Rob


----------



## Robby (Mar 1, 2013)

Took a look at the Rock Auto site.

G.M. pn 15263240.....$6.09 EA.

Standard Products pn TPM2011VK....$1.43 EA.

I don't know shipping costs but regarding Standard, most auto parts stores carry their line.....might want to give that a shot.

Rob


----------

