Tire pressure sensors are deeply conflicted

My 2006 Acura, which I’ve owned since September, 2007, has begun to give me apparently false reports of inadequate tire pressure. The indicator light kicks on immediately when I turn on the car but the tire pressure readings all indicate that none of the tires is at or below 27, which is when the indicator light is supposed to come on. This began about 6 months ago. I check the pressure when I turn on the car to be sure that it isn’t abnormally low due to cold tires but it shows the same pressure. The indicator tends to be kind of random–signalling only the front tires are low when the rear ones have lower pressure. Once, right after I gassed up the car, the indicator went off for a day. My dealer has tried valiantly but can’t find anything wrong after testing the sensors collectively and individually. I think they should quit trying to understand the problem and just try to fix it by replacing all the sensors. Any advice?

Just cause the Department of Transportation feels these devices are good for you, that does not mean YOU must concern yourself with them of spend money to maintain them. Millions upon millions of motorists have survived for over a hundred years without these nag lights and “safety features”… I bet you can survive without them too…

27 lbs of pressure sounds low to me.
Just because that is the pressure at which the tire pressure sensors are supposed to activate, this does not necessarily mean the 27 psi is a desirable tire pressure.

I suggest that you check the placard on the driver’s door jamb for the recommended inflation pressure. Then, inflate the tires to 3 lbs over that pressure, and drive the car for at least a few miles. There is a good chance that this will extinguish the light. And, you will experience both better handling and slightly improved gas mileage with this higher pressure.

Additionally, bear in mind that there is a sensor on the spare tire as well as the four tires mounted on the car. Even if the other four tires are correctly inflated, low pressure in your spare tire will activate the TPMS warning light. A friend of mine had this exact situation last month, and properly inflating his spare tire rectified the situation.

Check the spare. Some of these also have TPMS sensors in them.

True but it’s impossible to disconnect the system and it bothers me to have the indicator on continuously.

They did just that in late September but the problem recurred in November. They’ve checked the tires and found no signs of a slow leak. And the psi recorded by the sensor is well within the tolerance of the doorplate recommendation. I hadn’t thought about the spare tire and wonder if that could be the problem. I’ll ask the dealer to check. Thanks fr the suggestions.

Will try that. Thanks for the suggestion.

Why would you drive all the way to the dealership and wait for…God only knows how long…in order to have them do something as simple as checking the pressure in your spare tire?

Open the trunk, get out your tire pressure gauge, and check it yourself!
If this situation really bothers you, being able to resolve it yourself–with minimal investment in time spent at the dealership–will make the resolution all the more satisfying.

And, if simply inflating the spare tire properly is the solution to the problem, this should give you some idea of the insight and technical ability of the dealer’s staff.

My cheapy gauge shows the donut is massively underinflated. I’ve informed the dealership and am waiting to find out if this model has a sensor in the spare. I didn’t see anything but I don’t know what to look for. It would be both interesting and disheartening if this were indeed the the source of the problem, disheartening that they didn’t check it and that the “safety check” that promises to check all tire procedures has never been run.

So I’m assuming that when you check the tires with an actual gauge manually, that they are all up to the recommended pressure?

The dealer may actually be able to disable this feature if it isn’t working right, and they can’t fix it or it will cost too much. I know that on Chrysler vehicles, the system can be disabled but you need a scan tool that only the dealer will likely have. Not sure about Honda/Acura vehicles.

if it is a “donut” spare there is no TPMS for it.
get a good tire shop to reset all of your TPMS sensors. the tool they use will let them know if the system is working. it works on a radio frequency unless it is activated by ABS. all systems have a max and minimum pressure for in wheel sensors. do not exceed the max as this will also set the light on. if you have ever used “fix a flat” that can damage sensors. so can dirt in the inside of the tires if it gets into the actual sensor hole. you could also try to have the sensor serviced.IE new valve core, grommet, exterior retaining nut and valve cap. improper valve cores and or cap can cause TPMS problems
good luck

Is it legal to disable a piece of Federally-mandated safety equipment?

I really doubt that it would be legal, and as a result, I doubt if a dealership would do so. Just as it is not legal to disable or remove Federally-mandated emissions equipment, I doubt that it would be legal to disable safety-related equipment.

I didn’t realize that TPMS is mandated. I thought it was an option on my 2009 RAV4.

Could it be that I have TPMS and not know it?

Check your Owner’s Manual for the location of the TPMS warning light, and then see if it lights up briefly when you turn on the ignition.

IIRC, it became a mandatory feature as of 2008 (possibly earlier), at least on SUV-type vehicles.
By this time, I believe that it is mandatory on all new vehicles.

You never told us what the pressures actually are. All we know is that they are apparently more than 27. Please list the pressure of each tire.

On the day I delivered it to the repair shop, when the indicator light was on, I think the pressures reported were 31 (front left) and 30 for the other three. The reading this morning (again, as reported by the system rather than gauged manually) was 34 for 3 tires and 33 for another.

Since no one has pointed out the obvious, I will:

Your tire pressure gauge might be wrong.
I had one that was over 5 psi’s off when compared to two others that I own.

As for your dash telling you which tire is low, it sounds like the type of system where when your tires are rotated, you have to tell the computer where the sensors are located at.

If your tire shop forgets to do this, then when the right rear tire is only at 15 psi, the computer might indicate that it is the right front tire that is low, if this was that tire’s previous position before the rotation was performed, and the position adjustment not carried out.


Also, when were those readings taken? The 30psi reading if taken when the tire was warm could easily translate to 27psi when cold.

You seem to have forgotten that a tire loses 1 psi for every 10 degrees decrease in air temperature.

So, if it was 60 degrees in September the last time someone checked the tire pressures, and in November when the light came on it was 20 degrees, you would expect the tire pressure to be 4 psi lower in each tire.

That typically is enough of a pressure drop to activate a TPMS system, in most cars.


The readings I reported above were taken by the car’s computer (the built in indicator) when the car hadn’t been driven for a day. So the warning indicator reported low pressure when the TPMS told me the pressure was well above the 27 psi that should trigger a warning. Once the tire warmed up, a raise in pressure should have turned off the warning indicator had the pressure risen. I even turned the car off and on to reset the indicator but it immediately came back on. So I really don’t think any of the tires were low. I’ve checked the pressures manually both with my own gauge and at a tire store that happens to be just around the corner. They coincided. That’s why I suspect the problem is in the sensor or the computer. I’m going to wait and see if it recurs. If it does, then I’m going to hit them up for new sensors. Remember, I owned the car for 2 years before this problem arose.