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TPMS inconsistent

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Old Nov 17, 2018 | 03:56 PM
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Default TPMS inconsistent

My TPMS warning light has come on multiple times in the last month. I am not the first owner, so the sensors may be original from 2008 on my C4S. I am going to tire store to have them checked remotely. I have reset the system several times, and sometimes it has worked and others not. When working it has shown the pressures sometimes and other just the 0 or -1 for each wheel. Other times it will read both right wheels and both left wheels will not read and it says "Reg" or perhaps "Req". The light comes on some miles after this.

The sensors probably need to be replaced anyway, but I would still like to know if this is consisent with a bad TPMS receiving unit in the frunk. If that unit goes bad, would it read one side of car wheels and not the other? I found one other thread where someone got the same message no one confirmed that message "Req" means bad unit, which is a lot more to replace than a sensor. I would probably disable the system but do not have a durametric unit. My Indy said they could or would not disable it. Thoughts?
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Old Nov 17, 2018 | 08:36 PM
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Sounds like TPMS batteries. I read that ten years is about the max life. I would start by having the battery life percentage checked.
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Old Nov 18, 2018 | 09:17 AM
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If its a 2008 I would suspect the batteries. I have a 2010 VW where one of the TPMS batteries has gone, fortunately I could swap the wheels around to confirm its the TPMS unit in the wheel. Sometimes it works, sometimes not. Oddly they seem two work fine on cold mornings. Once I got a 100PSI readout on the dash! So low batteries can give you some pretty screwy readings...
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Old Nov 18, 2018 | 11:25 AM
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I suspect bstteries are bad. I am a little reluctant to spend $240 on new sensors to find out I need a new $3-400 TPMS receiver. Is there a way to test that unit other than replacing sensors and still having problem? I can live without TPMS but maybe not with warning light on.
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Old Nov 18, 2018 | 12:11 PM
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Could be the cooler weather. Mine go wonky every fall when low temps drop to the 40s. It's not my TPMS batteries since new ones from OEM Wheels were installed in 2016. When it happens I fill cold tires to 3 pounds under pressure rating and reset the TMPS. Good excuse for another drive then all is good.
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Old Nov 18, 2018 | 03:35 PM
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I had them turn mine off. Never been happier. Get an analog gauge from Sonnen......
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Old Nov 18, 2018 | 05:11 PM
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Originally Posted by ALEV8
I had them turn mine off. Never been happier. Get an analog gauge from Sonnen......
who did you get to turn it off? Indy or dealer?
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Old Nov 18, 2018 | 05:18 PM
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Turned mine off. They were a PIA. Indy or if your a member of PCA probably someone in the club can do it. 20 second job.
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Old Nov 18, 2018 | 08:00 PM
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Dealer did the work. About an hour. Durametic Pro can turn it off too. I found the PIWIS process here on the forum and handed it to them after being told it could t be done....LOL. No more pain in the *** TPMS @$250/ea and sketchy pressure readings.
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Old Nov 20, 2018 | 03:16 PM
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I had my sensors tested today. They all are working according to their test, although their tester doesn't evaluate battery life, just functioning and giving pressure reading or not. Since both left sensors seem to intermittently read or not together, that makes me think it is the receiving unit. Make sense?
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Old Nov 20, 2018 | 04:19 PM
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Swap wheels left to right and see if the problem moves with the wheels.

Durametric or PIWIS can read the battery life remaining
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Old Nov 20, 2018 | 10:58 PM
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Originally Posted by semicycler
Swap wheels left to right and see if the problem moves with the wheels.

Durametric or PIWIS can read the battery life remaining
i didn't think about swapping wheels side to side for some reason. Thanks
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Old Nov 22, 2018 | 02:41 AM
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my FL sender is on and off often, cold or hot
if two go wacky then I'll replace them-
(a spring '19 replacement)

~8 yrs is a good run for TPMS units

911 TPMS senders are $120 +/- @ P dealer
web prices may be 40% off, look hard
after market could be $150 for four, do not know quality

DavidA
'11 997.2 S
Blk/blk
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Old Nov 22, 2018 | 09:50 AM
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Nothing beats and old fashioned analogue needle gauge.
I check weekly.
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Old Nov 23, 2018 | 12:15 AM
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Originally Posted by wc11
Nothing beats and old fashioned analogue needle gauge.
I check weekly.
I have two high quality hand held tire pressure gauges and one cheap pencil shaped one. All three agree on a given tires pressure. I also check TPs every third or fourth trip. If my pressures are off by even one lb. I switch on the compressor and top them off. My newly acquired 997.2 has the TP monitors of course but I will still stick with my old ritual. This may be a stupid question but doesn't the tire have to be deflated or removed to install new sensors?
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