Okay,

I'm going to post some "n00bish" questions. My 2009 G37x Coupe is my first car with a tire pressure warning light.

Okay, first to explain the situation. I was driving home from my parent's place after a visit with them. I went to the store to pick up some last minute snack food items for company coming in tomorrow for Thanksgiving weekend. On the way back home, the tire pressure indicator light popped on. When I got home, I checked the pressure using an unplugged air compressor as a tire gauge (I lost my normal tire gauge). All 4 tires read 40 PSI. I have the stock wheels and tires, same tires from when I bought the car last year. For reference, the 2009 G37x Coupe takes the 18 inch wheels, and according to the manual and the decal in the door frame proper pressure for all 4 tires is 33 psi. Oh, it was about 0 degrees F, for those outside of the USA that's maybe -18 celcius or so?

(As an aside/Addendum: I always thought of anything cold air would cause lower pressure, so for them to read 40 psi due to extreme cold, that seems really backwards.)

So, my questions are perhaps obvious but to be clear:

1) Do tires when it's really cold (again 0F/18c) build up pressure? (I did wait an hour and check them again, still reading 40 psi all 4 tires)

2) Could the sensor malfunction at such a cold temp?

3) If the tires going to 40 psi due to the cold sounds right, should I just wait until it warms up (Should be closer to 32f/0c this Friday or Saturday) and then see if the warning light is on after I get the car up to speed? Or, should I bleed off some of the air, and then reinflate when it's only cold and not really cold like it is tonight?

Thanks in advance for any advice/suggestions. And please no trolling/flaming/suggestions that aren't directly related. This is My G37.com, not 4chan. :P &





EDIT: Problem solved. The tire gauge on my air compressor is broken, not sure how since it used to work fine.

I bought a new gauge, and used it and one I borrowed, both read about 26 psi on each tire, I assume due to the cold weather.

So, I inflated them to 30 (didn't go to 33 since we're due to warm up a tiny bit this weekend) and drove around for 10 minutes, the sensor shut down.

So, feel free to lock or delete this thread, issue solved.

 

Colder temperatures cause a drop in tire pressure, not an increase. I don't know why they be so high. I'm not sure if the TPMS would cause an indicator light from the pressure being that high.

 

Yeah, if you see my edit/addendum, I started wondering why it was reading high, not low. It could be my pressure gauge is off maybe though, since I was using an unplugged air compressor like a pressure gauge?

Now I did as a birthday gift from family a couple weeks ago have my car detailed, I suppose it's possible the detailer over inflated the tires for some reason, thinking they were low. But why wouldn't the sensor go off then, if overinflation would cause it? Again this only just happened late last night on my way home, my birthday was Nov. 8th and I had it detailed on the 10th if memory serves.

Anyway, I'll buy or borrow a gauge today sometime and check it with that before my company comes in, and go from there I suppose. And do one last check right before I start the car today using my air compressor also.

Thanks for the reply!

 

ADDENDUM/BUMP: As posted as an edit to my OP, issue solved. My air compressor gauge is borked, using another gauge I got the correct reading. Just needed to pump up my tires a bit. Sensor now off.

Moderators: Feel free if you want to lock or delete the thread to do so, issue is solved.

 

I would be interested know if anyone else is experiencing this issue that is not related to low tire pressure.

I live in Central Florida and three times so far this winter my TPMS gives me a warning about low pressure. Generally once the weather warms up (back in the low 50s) the warning light goes away. Now last winter we had quite a cold winter and never experienced this issue. One of my co-workers also has a G and is having the same issues. He took his back to the dealer and all they told him was to reset the sensor.

Has anyone else experienced these false low warnings on cold weather days?

Thanks,

 

Yeah, it's weird. My previous G coupe never gave me any TPMS warnings, though the two winters that I had it, even with very cold Canadian weather. However, my new 2010 coupe (this is the first winter with it) gave me a warner just a few days ago. I stopped at a gas station to check it, and it read 26 psi for all 4 wheels (which is the threshhold at which the TPMS warning will come on). I thought our tires cames with nitrogen, which is supposed to prevent large fluctuations in pressure. I mean, 33 psi to 26 is pretty big!

While on the subject, do you guys trust those gauges at the air pumps at the gas stations? I've heard some people say they're very inaccurate...?

 

lol last winted when it hit -56C in leduc not only did the TPMS come on but it was cold enough to shrink the crush washer on the oil pan and cause a leaak. Nitrogen can only do so much it will still contract just at a lesser rate then air. Just put some air in the tires and check it again when the weather gets warmer. once i week is a good call to check you tire pressure.

 

Hey Shumby,
That's pretty cold man, but hey I used to live in winnipeg hahaha. What's your opinion on the pressure gauges are the air pumps at the gas stations? I've heard some people say they are "very" inaccurate?

 

yes very. I keep a digital guage in the glovebox. it is pretty acurate and reads exactly what my tpms reads on the FX.