I bought a brand new '12 TL three weeks ago and have had no problems... and absolutely loving the upgrade over an '01 TL. This morning, after a really chilly night (35 degrees) in Chicago, my TPMS set off a low pressure alarm. Upon ignition, it was 27psi on all 4. As I started driving, it slowly increased to 29 and finally to 30 on 2 of the 4 tires. The weird thing is that the TPMS saw 3 of the four low, but the rear passenger (29psi) wasn't tripping the alarm, when both front tires were higher in psi and alarming.
When I called the dealership and asked if I should bring it in, he said that the TPMS is causing more harm than good and they've seen a ton of issues with them. He also said just to top it off and monitor them. My feeling is that I shouldn't have to do that for a 3 week old car with 850 miles on it. Am I overreacting? And has anybody else had this issue? Through my searches, I saw plenty of issues (mainly 3G), but nothing of this exact nature.

Any help is appreciated...

Thanks,
Brian

 

your PSI for those stock tires should be around 30-32 cold and 33-35 when warmed up.

pump your tires!

 

Cold air contracts.
warm air expands.

Over night, the ambient temperature dropped causing your air pressure in your tires to drop.
as you drive, your tires will heat up causing them to increase with pressure.

the 4G TL TPMS is set to alarm when the tire pressure reaches a threshold.
that threshold is 28PSI.

the proper way to inflate tires is to have a cold car, cold tires.
this means the car hasnt been driven for at least 4 hours.

you'll want to inflate them to the TL's factory settings; which can be found on a placard in your drivers door jam

 

Thanks guys... I understand that the air will contract in the cold... but didn't think that it should be enough to trip the sensors. I just wanted to make sure that there wasn't an install or integrity issue with them. It would be a bit more understandable in the middle of January when it's -10 outside...

 

Tire pressure drops about 1 psi for every 10 degrees F.

if tire pressure was around 33-34psi cold at lets say 75 degrees
it would be normal or within range of dropping to 28-29psi at 35 degrees.
Again the threshold is 28psi.

you can always get out a tire gauge to see if TPMS is accurate

 

I've owned Hondas and Acuras for the past twenty years and I noticed the same thing when the temps went down. My Honda tech told me that as a rule of thumb for every ten degrees the temp drops, the psi will drop by 1lb. Don't know how accurate that advice may be but living in San Antonio when the weather can fluctuate 40 degrees throughout the day...it seems pretty accurate. The bet way to avoid the fluctuation is to fill with nitrogen. The dealer won't do it but your local Costco will and you won't have to worry about temp affecting psi.

 

There is solution to avoid fluctuation....fill with nitrogen and your problem will go away.

 

Incorrect.

In addition, I find it incredible that the OP complains about the TPMS system when the dealership probably never checked the tire pressure during PDI.

 

Hi Brian,
I don't think you are over reacting. While the TPMS might not be 100% accurate it it fairly close and when you pay that much money for a car you should expect it to work right regardless of what the dealer says. I would push the issue if you "continue" to have problems with it.

 

Nitrogen will slightly lessen the pressure swings due to temperature, but not eliminate them. Nitrogen is less apt to migrate through the rubber than air, which is good, and it is also dry, which is also good. So it's a good idea regardless. My dealership does nitrogen fills, so I would say that it's one of those things that depends on your dealership.

My car (still with stock tires) sits at about 33PSI cold in the garage (50-70 degrees depending on time of year). I've seen it dip down to 29 or so when it's been below freezing outside but it recovers quickly once the tires warm up.

 

^^^ I agree. Even with nitrogen, I see see some fluctuation with my TPMS reading.

 

Price of the car has nothing to do with it. If the tires were close enough to the threshold cold when it got colder out they would most likely trigger the warning. It wouldnt matter if it was on a 200k car or a 20k car. It would happen. Inflate the tires properly and maintain them (ie check them yourself regularly) .

 

I'm referring to the issue of his system not going off when one of the tires was lower than the others that were tripping the system. Not that 29psi should trip the system.

 

Justin nailed it .... it's not a problem with the car, it's just cool weather.

When the seasons change you need to make some adjustment to pressures. Once they settle in, just manage them as normal with an occasional bit of air if needed.

 

You need to understand both the purpose and the mechanics of the TPMS system.

It was not intended (nor designed) to replace regular tire pressure checks. It was intended and designed to alert the driver of dangerously low pressure that could lead to a catastrophic tire failure.

By law, the system must alert (at least) when the tire pressure falls below 75% of the intended pressure. Acuras tend to alert earlier (which is good) but the TPMS was never intended to be an accurate measure of tire pressure and a comparison between the figures shown on the dash and the actual pressures taken with a reliable gauge (which may also not be accurate) may lead to wildly differing readings.

Different manufacturers have different methods of working the TPMS. Some have a system reset where you set the correct pressure, then tell the system that it is correct (most European manufacturers) while others have the "correct" pressure hard coded into the sensors - one reason that a sensor from one Acura may not work correctly with a different Acura even if the sensors are recognized by the system and show tire pressures on the dash.

Let's assume that the "correct" pressure is 33psi for the TL. The sensors are probably set to 32psi in that case. Accordingly, to comply with the law, they must alert in the 24 to 25psi range. If yours alert in the 28/29 range then that just means that the threshold is tighter.

Tire wear increased measurably when tire pressures drop by about 10% so alerting at 28/29 is a good thing but the system is not malfunctioning unless it fails to alert below 24/25.

If anyone is interested, I can discuss the reasons why the 25% threshold was set.

Few people (including techs at the dealership) have a clue about how TPMS works so you'll get a variety of (mostly wrong) answers.

TPMS does not replace monthly checks. By the time the system alerts you may already have increased wear. A "normal" undamaged tire loses about 1psi per month and the pressure fluctuates by 1psi for every ten degrees of temperature change (about .85psi for nitro fill). Accordingly, if you got your car prepped at the dealership in July (90 degrees) then your car will have lost about 3psi by time and another 5psi or so based on temps.

 

While I accept this as true and accurate, I have compared my 3G TPMS output/display against the tire pressure guage I use and there is, in my case, a high degree of correlation. Both guages read the same on 3 tires; on the 4th there is a ~1/2 PSI difference (I assume it's about 0.5 psi since sometimes both guages are the same and sometimes they are 1 psi different).

Since this correlation has held for a long period of time and across a wide range of temperatures, I am very comfortable using the TPMS display in the MID as a tire pressure monitor and do so regularly.

IOW - if I set my pressures at, say, 33F / 36R according to my guage, the TPMS MID display shows the same and I can monitor that for changes. When one (or some, or all) pressures change, I can make decisions on adjusting air pressure from that.


Moral of the story: If you have a reasonably reliable guage you can correlate that to the TPMS display and use the display to monitor pressure. You should, however, confirm the correlation remains consistent as time passes.

 

Correct. If you do the test (you did) then you know that it holds true for your car but everyone needs to test it for themselves. This is especially true if you're using a sensor you bought on eBay or with a set of aftermarket wheels/tires.

 

Let this be a lesson to the rest of us. I'm checking the the tire pressure in both cars when I get home.

 

One of the main issues that wasn't addressed is why the TPMS is tripping the alarm for 3 of the 4 tires... and the one that isn't being tripped has a lower PSI. It's very inconsistent. It's not a huge problem, but makes me not want to rely on the technology that is supposed to help.

Thanks for everybody's responses.

 

Very simple and you really answered it yourself. By the legal requirements, the sensor must alert at 75% of the manufacturer set pressure. Like I said earlier, that would be in the 24/25psi range. In your case 3 of the four sensors alert early (which is good) but that by itself does not indicate a problem.

 

Last winter when it was below zero temp outside my tpms sensors went off in the car's MID.

I had checked the tire pressure the week before when it was in the 20* - 30*F temp. range.

So the extreme cold temp had alot to do with the low air pressure. It's a good idea to check tire pressure at least twice/ week when the temp drops!