Low tire pressure warning

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Ken7

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This morning, despite all tires having a minimum of 37psi, I got a low pressure warning. I checked with 2 gauges and both indicated that no tire was below 37. The recommended tire pressure is 35. So I'm not sure why I got this warning. True the temperature had dropped to the low 20s, but the tires were still reading at or above 37.

I'm going to do a calibration as suggested in the manual to see if that takes care of it. When I picked up the car new from the dealer, they had the tires significantly overinflated to 45psi. That gave a harder ride, so I dropped all tires to 37-38psi.

Has anyone gotten this warning despite pressures being at or above recommended pressure?
 
Are you using a tire pressure gauge to check your tire pressures? It is possible it is reading off. There is a calibration procedure you can follow as well in the full owner's manual, page 425.
 
Viking79 said:
Are you using a tire pressure gauge to check your tire pressures? It is possible it is reading off. There is a calibration procedure you can follow as well in the full owner's manual, page 425.
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Yup, 2 different tire pressure gauges plus a portable air compressor gun designed for filling tires that also has its own gauge. All read within 1/2lb of each other.

I performed the calibration and the warning light went off until I was on the way back home. The light then came on again. So now I've filled all tires to 40lb to see if that helps. But it seems if the recommended tire pressure is 35lbs, anything at 35 or above should not trigger the warning light. In fact, I would think, even a tire pressure of 33lbs shouldn't trigger the warning light.

I'm beginning to think one of the tire sensors is defective. :(
 
"Tire Pressure Monitoring System (TPMS) - Instead of directly measuring the pressure in each tire, the TPMS on this vehicle monitors and compares the rolling radius and rotational characteristics of each wheel and tire while you are driving to determine if one or more tires are significantly under-inflated." {Anyone know what the sensor is? Is this TPMS sensor even in the tires?}

As part of my Pirelli tire fiasco, just to add misery, I was out touring in hill country Sunday afternoon when I got the dreaded TPMS light and warning. It took a bit to find a safe place to stop where the snow and ice wasn't too bad. I just walked around and kicked the tires and nothing looked too low.

I forgot to put my gauge in the car, so when I go home, I measured 36 all around, except for one of the fronts which was already problematic for out of round, now had dropped 6 lbs to 30. I suppose if it was really bad, I could have used the gauge on our on-board 12V air pump, but it was so cold and snowy and icy, I didn't want to mess with it. The installer set them all to 36 per the door jamb label, I may run at 40 like I did in the Volts, not sure yet.

So, I did some TPMS owner's manual reading too. Our system is a bit odd. Not only does it not read tire pressure in the cockpit (the Volt displayed all 4 tire pressures), but it only looks at differences between the readings. If I read the instructions correctly (still learning), any time you top them off or change pressure, you must do a TPMS system cal.
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Tiralc, that’s exactly how I interpreted it. It’s bizarre that you have to recalibrate the system once you add or subtract air.

I can tell you going from the 45psi the dealer delivered my car with, to the 36psi I set it to later, greatly enhanced my ride. It’s annoying that simply dropping the pressure to what is recommended on the door label, has begun this low pressure warning issue. It makes no sense that I had no issues until I adjusted it to the 36psi recommended readings. :(

Tonight I added air to 40psi in all tires (again checked by 2 tire pressure gauges and the gauge on the portable tire compressor’s gauge). I’ll recalibrate again tomorrow morning. Maybe that ‘compromise’ will work, but it’s nuts that I can’t set it to the recommended 36psi that maximizes the ride comfort.

PS: I may have forgotten, but did you swap your Michelins for Pirellis?
 
>>did you swap your Michelins for Pirellis?

yes, I've been holding off talking about it much so I can sort things out. My reasoning was that I don't really need snow tires (most days I can wait for the roads to be cleared), but I'm not sure the eco-savers snow performance is good enough for those times I get caught in an odd storm. The Volt group spoke very highly of the Pirelli P7s over the years. I always used Michelin Pilots, then the Premiers.

So, I got the P7s thinking I would sell the "new" OEM Michelins. A day after installation, I had a noticeable vibration above 45 mph. So, I went to another local installer who does more specialized high end work. He significantly improved the situation, but two remained marginal for out of round and there is still some vibration. I was almost ready to live with it, but then the vibration got worse again, and I lost 6 lbs in one day in one of the out of round tires and got TPMS (a correct warning). Also, first impression are that the P7s are noisier which surprised me. My tire expert noted no surprise because of the different tread and deeper channels. Now, I'm thinking I'll put the Michelin ecosavers back on late spring through early fall (or buy a second set of rims, not sure).

Gen 1 Volt going from the OEM Goodyear to Michelin Pilots was night and day. Gen 2 Volt, from Michelin ecosaver to Michelin Premier was a very slight improvement overall, but better in snow. Now, MEH, I regret not thinking more about actual snow tires, or maybe the Continental PureContact. Oh well. TireRack says they will make good on some of the extra installation expenses, if that works out, I may be pleased with them, we'll see (seems promising).

Even though I am less than thrilled with the Pirelli P7s, I have already got caught 2 or 3 times in surprisingly bad snow / ice road conditions, and the P7s do appear to have a better grip compared to the regular ecosavers. Ironically, after reading such high ratings all around at tire rack for snow / rain P7 performance, now some are saying the P7 is does less well in rain, not sure what that is about. A tirerack advisor said that was true in their latest track testing, but that most road drivers were still giving the P7s very high ratings including rain.
 
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Tiralc, I’m actually not at all surprised that the Pirellis are noisier. I say that only because I find the OEM Ecos to be so quiet, I’d be surprised if there’s another tire out there that’s significantly quieter. I can tell you it’s embarrassing that there’s more road noise on my Tesla, with its Good Year OEM tires, than the Clarity. Interestingly, last night as we were riding in the Tesla, my wife commented that the Tesla ride was firmer and she preferred the softer ride of the Clarity. Hmm.

She is right though, the Clarity’s ride is softer and less road noise seems to intrude into the cabin, despite the Tesla being a very quiet car on its own. I often wonder if I can get significantly quieter tires for the Tesla. OTOH, the Tesla handles and corners better, even though the Clarity is now slouch in either department.

I am surprised that the P7s offer less grip in the rain, but I’m not surprised they do better in the snow. We’re expecting our first ‘real’ snow here in NY this weekend. So I’m curious to see how the Clarity does. If it’s really bad, we just won’t go out. I’m not as brave as I used to be...or I’m wiser, not sure which. ;)

Back to tire pressure and the TPMS. I did set all tires to 37-38 yesterday and recalibrated. All was well as the system was calibrating (the light went out) until late in the day when the TPMS warning light came back on. I rechecked the tire pressures to be sure, and none had lost any air. Screwy.

So today I’m up to 40psi and I’ll recalibrate again. If that too fails, I’m off to the dealer to let them look at it.
 
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We had this problem with a new Clarity at the start of our cross country trip. The warning came on despite even tire pressure in all four wheels, but the problem went away after recalibrating and traveling to warmer climes.

Now we are about to go back up into cold country and i am wondering if the low pressure light will come back on. Will know in a few days.
 
We had the warning early on and also yet all tires were at the appropriate tire pressure. It took 2 recalibration cycles to get things right.
 
Glad this thread was still around. Happened to me today. One tire was 34 PSI, and apparently that set it off. Then the light wouldn't go away even after resetting via settings. Now I know why. This is literally the first "light" that's come on in this car - almost one year old. Can't complain about that.
 
bfd said:
Glad this thread was still around. Happened to me today. One tire was 34 PSI, and apparently that set it off. Then the light wouldn't go away even after resetting via settings. Now I know why. This is literally the first "light" that's come on in this car - almost one year old. Can't complain about that.
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Triggering at 34 PSI, cold seems pretty sensitive. I've had one go off at about 30, after a nail caused a slow leak. I've been tracking tire pressures carefully and often, and touching them back up to 36 since that happened. My tires all lose about a pound of pressure every 20 days, or so. I don't know if that is typical, or not, but all four of them behave the same way.
 
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