Bad TPMS?

[goodmaj]

A couple of weeks ago I drove from STL to Michigan. The next morning, I had a low tire warning in the left rear. I found a local tire shop and they dunked the tire in water but could not find a leak, I was right next to the tech when he did it. I chalked it up to temperature change (though my tires are supposedly filled with nitrogen), put some air in it, and headed home without incident.

Tonight, I got into the car after work and sure enough got another low tire warning in the same tire. I checked the pressure and it was around 32 PSI - I can't completely recall, but I'm pretty sure when I filled the tire in Michigan that I went to 35 or 36 PSI.

Given that there apparently weren't any leaks a couple of weeks ago, it seems like an odd coincidence that I got the warning in the same tire a couple of weeks later. Is there any record of TPMS sensors going bad, or do I just have a really, really slow leak? I'm running Bridgestone RFTs, once they go I'm switching to conventional tires and buying a spare kit.

[bmwx5er]

Originally Posted by goodmaj

A couple of weeks ago I drove from STL to Michigan. The next morning, I had a low tire warning in the left rear. I found a local tire shop and they dunked the tire in water but could not find a leak, I was right next to the tech when he did it. I chalked it up to temperature change (though my tires are supposedly filled with nitrogen), put some air in it, and headed home without incident.

Tonight, I got into the car after work and sure enough got another low tire warning in the same tire. I checked the pressure and it was around 32 PSI - I can't completely recall, but I'm pretty sure when I filled the tire in Michigan that I went to 35 or 36 PSI.

Given that there apparently weren't any leaks a couple of weeks ago, it seems like an odd coincidence that I got the warning in the same tire a couple of weeks later. Is there any record of TPMS sensors going bad, or do I just have a really, really slow leak? I'm running Bridgestone RFTs, once they go I'm switching to conventional tires and buying a spare kit.

TPMS have batteries in them, which have a life of about 4-5 years (IIRC). If your car was manufactured in 2010 - 2011, it could very well be the TPMS going bad. I believe tire rack sells TPMS sets for about $140.

If you're noticing a drop of 4psi in a couple of weeks, it could very well be a slow leak.

[mitch808]

My dealer was able to use some sort of scanner to find an intermittent bad TPMS. If you have the time, and deductible, do it.

[goodmaj]

Thanks guys. I reset the monitor at 31 PSI and am going to see what happens. If it keeps failing I'll have to get it re-dunked or perhaps get a new bead. I spoke to my friendly SA who indicated that if the TPMS was failing the tire wouldn't have lost pressure but the sensor would have fired.