dacoffee

Hello,

I am new to this forum, I am sorry if this question has already been answered.

I own Civic LX 2011 Model (42k miles driven, this was a certified vehicle when I brought from Honda dealer 2 years back). About 2-3 weeks back, I saw my first TPMS indicator flashing on dashboard. I googled it up (sorry, I am a newbie) and found out that this happens when the pressure is either less or more than what it should be.

I took my pressure gauge and went to gas station. Checked tyre pressure and sure enough I found the front tyre had 31.5 PSI while the rear ones had 36 PSI. I balanced it out and kept 32 PSI in all four tyres. After driving for few miles, the light went off and I was happy until yesterday night when the TPMS light again came on.

I checked the pressure and instead of 32 PSI the pressure was between 33 and 34 in all four of them. I removed some air and its again 32 in all of them.

My questions are:

1. Why did the pressure increase on its own? I am sure it was 32 when I filled it last time.
2. Should I be concerned about this or is this a usual activity? I thought that pressure might increase due to increase pressure during Summer but this could be totally stupid reasoning.
3. What is the threshold below or above which it becomes dangerous to drive? I want to ensure I am not risking myself or my car.

I will really appreciate expert comments. I am now feeling scared taking my car out on highways

Best!

lowlife9

when you drive your car the tires heat up from friction which expands the air inside,this alone can raise the air up 2-4 psi. not to mention the ambient temperature outside and the temperature of the road surface.i alwaysfill up with 32 psi in the summer. the max tire pressure is located on the sidewall of the tire which is probably alot,like 50psi. i sometimes run 35 which increases gas mileage but drastically reduces ride comfort. i know some people that run 40psi which must feel horrible.

ezone

As explained, pressures change as a direct result of temperature changes.
(Chemistry and Physics 101).

It's generally stated that tire pressures can change about 1PSI for every 10 degrees F change in temperature. Driving raises tire temperature, as does brake use....and pavement temperature, and just leaving the car sitting in the sun might get half of the tires hot...

Tire pressures are supposed to be set with the tire "cold", like morning ambient temperature before driving or having the sun heat them up. Set them cold and do not remove air if you find them higher than what you set them, they will come back down when the temperature drops again.

In my area temps can swing wildly, sometimes 40*F in a day or 60*F or more in a weeks time. (I set tires rather high because of this.)


The owners manual should be your first reference source!

The low pressure icon "(_!_)" is different from the "TPMS" warning light.
Which one did you have on?



The (_!_) warning light comes on when tire pressure drops to around 26 PSI (don't know your actual setting, but that's going to be pretty close) and turn off when pressure rises to around 29PSI.


You could easily have a very inaccurate tire pressure gauge....the cheapies from the Walmart checkout aisle are cheap for a reason. If you get a dozen of them and check the same tire with each one, you might get 8 different pressure readings!

A sensor could be inaccurate, that can be tested by the dealer when they check out the warning light (if necessary).

The "TPMS" warning light comes on when there is a failure somewhere within the tire pressure monitoring system. Actual tire pressures are not relevant when this light comes on.

There are several possible causes, including pressure sensor failure, RF signal interference, or control unit failure. The only way to figure this out is to read the fault code(s) in the TPMS system and then begin to diagnose why it set.

I've seen where laptop, cellphone, and a cellphone charger can cause enough RF interference to cause fault codes in the system.