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Faulty TPM sensors?

fireblade

fireblade

PCGB Member
Member
Hi

Just had a big orange dashboard warning that my two left tyres are well underinflated!!

Pressures checked and spot on exactly the same as the right side plus the ordinary TPM screen showing all pressures correct and the same as my gauge

Irritating as I am on the ferry tomorrow for a track day at Fontenay-la -Compte but no time to get to OPC beforehand.

Any ideas for a quick fix, I don't like having a permanent warning light on particularly on the track.

Cheers
 
Funny you should say that as last weekend I took my 911 out and one of the rears was displaying 40 psi (warm target) from cold with the other 37 psi (normal for cold).

As I drove along it then shot down to 36 psi, then flickered between 37 and 40.

30 mins on the motorway didn't cure it but some spirited cornering then put the readings all to:

34 - 34

40 - 40

...where they should be.

I concluded that the TPM sensor in the wheel probably needs a new battery (6 years old) or was maybe a bit loose or had some dirt in it somehow and some fast rotations of the tyre sorted it.

So hopefully a bit of driving will sort yours too. Otherwise I'd suggest stopping, resetting the TPM sensors through the dashboard and it relearn/reset them as you then drive.
 
Actually reading the 911 Turbo drivers manual (997.1) it says unloaded pressures cold (20 degC ambient temperature) should be:

33 - 33

39 - 39

However, there is also a chart that shows target pressure changing with temperature which has it at 36 psi cold (20 degC) and 42 psi warm (60 degC) as the targets. So somehow need to chart the same for the front and rears above...

 

ORIGINAL: Alex L



I concluded that the TPM sensor in the wheel probably needs a new battery (6 years old) or was maybe a bit loose or had some dirt in it somehow and some fast rotations of the tyre sorted it.

So hopefully a bit of driving will sort yours too. Otherwise I'd suggest stopping, resetting the TPM sensors through the dashboard and it relearn/reset them as you then drive.
Click to expand...


Thanks Alex, car new in February so sensor batteries should be OK. I reset on dashboard as you suggested and while it is relearning at least the warning light has gone out! Hopefully this has solved the problem and I will find out tomorrow after I put a few miles on.

Cheers

Michael
 
I asked my OPC about the battery life of the sensors and they told me 3 years. Mine have been going for 6 - so next time I change my tires I will change the batteries too...
 

ORIGINAL: Alex L

I asked my OPC about the battery life of the sensors and they told me 3 years. Mine have been going for 6 - so next time I change my tires I will change the batteries too...
Click to expand...

Mine were still going strong when I sold it after five years and as far as I am aware still are although after three years one developed a fault and I was told the unit was replaced under warranty but of course they might just have change the battery!!
 
I think you will find that the batteries are not replaceable. Complete new units required, which at Porsche prices is significant! Fortunately available elsewhere at more competitive prices.
 
I was told about the batteries by the head of the parts dept at OPC Reading - he certainly didn't indicate whole new units were required and suggested it was a quick and cheap procedure.

I am going to call the service dept to clarify...
 
You are right Geoff - sensor and battery are one closed unit so the whole thing needs to be changed.

It's every 6 years according to the service dept.

Cost per TPM unit is approx. £102+VAT + fitting and re-coding = £180

Trouble is I can't do this next time I change tires as I use Michelin Pilot Super Sports which aren't N rated for 997s - so the OPC wont fit them.
 

ORIGINAL: Alex L

You are right Geoff - sensor and battery are one closed unit so the whole thing needs to be changed.

It's every 6 years according to the service dept.

Cost per TPM unit is approx. £102+VAT + fitting and re-coding = £180

Trouble is I can't do this next time I change tires as I use Michelin Pilot Super Sports which aren't N rated for 997s - so the OPC wont fit them.
Click to expand...


I guess that is why my faulty unit was replaced under warranty, it wasn't just a battery. What a rip off!!
 

ORIGINAL: Alex L

I asked my OPC about the battery life of the sensors and they told me 3 years. Mine have been going for 6 - so next time I change my tires I will change the batteries too...
Click to expand...

The OPC that told you 3 years is taking the P.

I have just checked here, battery life for 997 sensors is 90 months from first activation (+25 PSI applied for 2.5 minutes)

Those lucky 991 owners can expect 120 months as the sensors are diffferent.
 
My experience (with a number of non-porsche-branded sensors) is that battery life is severely reduced by unattended low pressure events - for example when car is sat in garage with a slow puncture. You come along to drive your car and find the sensor in the wheel has gone mad trying to urgently update the console for the last couple of weeks and used up most of its battery.
 
Available in sets of 4 $200-$300 here:
http://www.oewheelsllc.com/TPMS-Sensors_5/TPMS-Sensors-sets-for-Porsche#.VFD_mBsqWUm
Other suppliers available.
So even if battery life is less cost saving is huge.
You don't need to remove the tyre to fit, just break the bead and push tyre down next to valve to expose unit.
 
Thanks for that link Geoff. I have a Cayenne on order which now has TPMS as standard so need to get a set for the winter wheels (which fortunately had sensors originally). So just need to figure out which is the correct set to order.
 
Take a look in the 997 Register Technical Section Index and there's a post which has a link there to some locally supplied TMPS sensors.
You just need to make sure the transmission frequency is the same as the ones you're replacing.

Regards,

Clive.
 
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