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I bought a used car a few years back that has a Tire Pressure Monitoring System (TPMS) including a readout on the dash with the pressure level on all tires and a warning indicator when any of the tires is more than 10 pounds under-inflated.

Since I bought the car, I've noticed that the TPMS intermittently won't get a reading on one of the tires and shows * for the PSI and the flat tire indicator will light up on the dash. It seems fairly random which tire(s) are not getting a reading and many times it will correct itself either later in the same trip or the next time I start the car.

At first I thought there might be a battery in the device mounted on the rims that was going dead, but I'm going on 5 years of having the problem and it still goes in and out on the various tires.

I'm not exactly sure how these things work, or if they even have batteries in them. So I'm not sure what to blame the issue on. Are these things just generally flaky? Could all 4 of them be defective (it has indicated a problem on all of the tires at one time or another).

If the tires were right on the borderline of being the right pressure, I could see temperature pushing them over the line, but I'd assume in that case it would just show a low PSI reading and not a *, which I assume means it didn't get data from that tire.

Any ideas what might be causing this?

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Make, Model, Year? –  Larry Nov 1 '11 at 22:21
    
Infiniti, M35, 2006 –  JohnFx Nov 1 '11 at 22:39

1 Answer 1

Sadly, I don't know which of the two main types of TPMS Infiniti use, powered or passive (see this Wikipedia article for some explanation), but my guess would be powered, and that one of the chassis mounted antennae is marginal on gain so has trouble getting a reading under some conditions.

Maybe the antenna has had some damage - worth a check.

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Common to get corrosion around antenna connections. Should have been sealed from the factory, but sealant does wear out and fall off after a time. –  Brian Knoblauch Nov 2 '11 at 12:15
    
Also, wire damage can have some effects similar to this. I had an X5 once that had been attacked by rats, and I found the wires on the wheel well had been chewed and affected TPMS and ABS. –  FossilizedCarlos Nov 2 '11 at 22:35

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