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Discussion Starter #1
I've had two instances when the Volt's TPMS has flipped out and indicated that all four tires are at "--" pressure; not "zeros", but dashes. Both times were during a hurricane event and both times all four tires were properly inflated. The first time happened when I was evacuating from Hurricane Matthew and then it just happened again with Hurricane Irma. Coincidence or is there some connection with barometric fluctuations related to hurricanes?
 

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The dashes usually indicate that the vehicle can't communicate with the sensors.
 

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Radio Frequency interference would be my guess. Hurricanes are "loud" in the RF bands.
 

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agreed that communication was lost between the TPMS sensor and receiver. I had a flat a few months ago and swapped the wheel with another Gen 1 wheel I had and that one corner just showed "--" but the others worked fine. I had to reset the TPMS system to get the replacement wheel to give a reading. Being that TPMS has s pretty short range, it wouldn't surprise me that high levels of RF interference would reduce or eliminate any chance the receiver has to getting a clean readable signal from the sensors and instead give an indication it couldn't read by displaying "--" rather than potentially faulty information.
 

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I've seen the dashes when pressures are so far from normal that it seems to assume it can't be correct or usefully meaningful.
I think I saw something in the manual about it too.
 

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Hurricane Irma's eye pressure was around 1.5 PSI less than normal sea level pressure, so I would expect the tire pressure to go up that much at most. This is pretty negligible as it is easy to have a 4 psi change from temperature driving around. My thought is it is not pressure related.
 

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Discussion Starter #8 (Edited)
Hurricane Irma's eye pressure was around 1.5 PSI less than normal sea level pressure, so I would expect the tire pressure to go up that much at most. This is pretty negligible as it is easy to have a 4 psi change from temperature driving around. My thought is it is not pressure related.
Yeah, my thought was that the TPMS didn't like changes in pressure at all four wheels when the car isn't moving, but I think the RF interference theory make much more sense if it isn't simply coincidence. It was just odd because my wife's car (2015 Ford Escape) was also incorrectly registering low pressure from TPMS at the same time (not during Matthew, just Irma for her car).

I've never had an incorrect TPMS reading from the VW Thing. :)
 

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Were you using some electronics during the evacuation that you normally don't (e.g. GPS)? I've had TPMS interference from using a "noisy" aux power plug in the top cubby, but it sometimes took 20-30 minutes to manifest, so it might not be noticeable if you normally take only shorter trips. Once I stopped using that top power jack, I haven't had any issues (well, except from a dashcam).

Oh, you have a gen2 which doesn't have the top cubby... but still, anything noisy placed up there could cause interference.
 

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Barometric pressure changes should not affect TPMS because the sensors are inside the tires and they measure absolute pressure, not pressure relative to ambient.

Are you running any extra electronic equipment inside the car when evacuating that could cause radio interference? Maybe a Garmin, extra phone charger, dvd, etc.?
 

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Discussion Starter #11
No extra electronics. Just the normal iPhone and iPad connected through CarPlay.
 

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Do you normally run both an iPhone and iPad in the car, or is that unique to evacuating? If it is unique, there might be something to look into there. Those devices can be sources of radio interference (bluetooth, wifi, cellular), and the way that they are charging can also potentially be a source. Also running both at the same time rather than either one separately can produce twice as much interference, which may be more than the TPMS can handle.
 

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Discussion Starter #13
Do you normally run both an iPhone and iPad in the car, or is that unique to evacuating? If it is unique, there might be something to look into there. Those devices can be sources of radio interference (bluetooth, wifi, cellular), and the way that they are charging can also potentially be a source. Also running both at the same time rather than either one separately can produce twice as much interference, which may be more than the TPMS can handle.
Very common set up on any trip more than 30 miles. The iPad is just running Waze and the iPhone is on CarPlay doing everything else except Navigation. Both are on the car's WiFi and both are plugged in to the USB ports in the front center console. On short trips, I leave everything unplugged and just use bluetooth.
 

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I've been advised by my dealer to be cautious about tire choice, because the TPMS comms can be effected by the steel belts in the tire carcass.
I expect that the belts would be insulated from the wheel, (not grounded), so could pick up RF and shield the signal.
 
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