Tire Pressure Monitoring

[allanjenkins]

Used the car today first time for three months! you really do forget how good they are, had a great time.

After a while a warning indicator appeared on the instrument cluster to advise that the tire press monitoring was inactive and eventually the red exclamation mark ! came up.

Pulled over and went through the check pressure routine and it was showing only the RHS with actual values while the LHS had "req'd" next to it. Shut the engine down for 30 secs or so, restarted and all was good on the instrument cluster, but still the same on the check display, only RHS had pressures displayed.

Drove off and after a while the same routine happened. So there seems to be a problem with the LHS, strange that its each wheel though? must be something to do with the control module I'm thinking.

Does anyone have any experience with these systems? Any assistance would be appreciated.

[Lee 944]

I don't have it on my 996, but did on the 928. They're not very good as it's a metal sensor on an alloy wheel. Corrosion gets in and stops it transmitting. There is more chance of it being the transmitter in the wheels than the control unit I think? If you're really keen you could swap the tyres and see if the fault moves? Other than that you'll have to get your flexible friend out.

[Lee 944]

Sorry I meant swap the wheels over, not the tyres.

[allanjenkins]

Thanks for that Lee, I'll give it a go in the morning. I've read that the transmitters have batteries in them with a life of around four years, my tires are comming up to three years so maybe related. Swopping the wheels & tires over will prove that one way or the other. I still think it odd that two have gone together??

Of course when I went to the car this morning and fired it up two additional faults came up, PSM/PASM. Was thinking it must be battery low voltage related, but everything checked out OK. Decided to take it out for a run, a steady one, for 20 miles or so, stopping and shutting the ignition off a few times. It cleared the two new faults but not the tire pressure monitoring issue.

Think it's time to order the Durametric.

[Lee 944]

Members have a discount code for Design 911, who sell the Durametric. I'll check and see if it's in All Torque?

[allanjenkins]

Yes it is and they offer a 5% discount, but the product sells for much more than Hickleys, who are the authorised importers and distributors of Durametric. After vat and delivery and taking the discount off they are about £50 adrift.

[garyw]

I sometimes had a similar issue when the car had stood for a while.
A good drive out usually sorted it - a 20mile drive is a run round the block in my books and probably not doing it any favours as things are only just getting warm by then!
Anyway a good run and after a coffee it normally sorted all the faults.
I never had new batteries fitted in my TPMS and that was after 55K in five years - but very pleased I had it as it did work properly twice

[allanjenkins]

Changed the front wheels over today, no change though! will try a long run this week and see if that does the trick. I'll also chase down the exact location of the control unit and have a look at the connections, disconnecting and reconnecting may help?

[allanjenkins]

Found out that on a 2007 car the wheel sensors are individually coded so changing over the wheels does not work and would need to be recoded to get it to work with the control unit, so I need to change over the front wheels to get them back to where they were.
This has changed on current generation cars, where they are capable of being changed over without affecting the system.

I also adjusted the tire pressure on the RHS but it didn't transmit to the instrument cluster, so I think the whole thing has frozen.

Discussed this with Leicester OPC who advised disconnecting the battery for 10-15secs then taking the car out for a long run, more than 20 miles was their suggestion. They also confirm the sensor issue above. Hopefully I'll get to do this on the weekend.

Interesting to note on 2012 cars this is an MOT fail but only an advisory for anything older.

[allanjenkins]

Changed front wheels back, disconnected battery and taken car out for a long run. But still no joy with TPM. Durametric ordered (been thinking about one for a long time now, just needed a reason) and on it's way, we'll see if that can identify what exactly is causing this issue.

[allanjenkins]

Durametric tool arrived, hardware & software installed.

There were quite a few fault codes present mostly to do with the steering wheel geometry and instrument cluster. Think they were related to me disconnecting the battery a few days ago. Cleared the fault codes and took it out for a run then checked the codes again.

This time only one present. TPM - 800A - wheel electronics rear left.

As it's the LHS that is not registering on the instrument cluster I think the Durametric has done it's job.

Next step is to investigate the wheel sensor/battery replacement.

[Lee 944]

Keep us posted, looks like progress....of sorts.

[Chris_in_the_UK]

When I had the same issue on my 2007 Cayman S I discovered the following:-

Sensors are not coded individually - swapping wheels is not really an issue.

The batteries are not replaceable in the wheel sensors.

Porsche wanted circa £230 per wheel for the sensors plus fitting.

I sourced some OEM ones from here:- http://www.rlauto.com/TPMS/index.html they were very helpful and I paid around £70 each from memory.

Local ATS removed the old sensor & valve assemblies, fitted the new ones, balanced wheels and did a nitrogen fill on all four wheels for £25 all in.

All I then did was drive the car for around 15 mins - error message disappeared off the dashboard and the system was back working and has been fine for 9 months.

Hope this helps?

[allanjenkins]

Thanks for the info. Yes I now agree that the sensors are self learning and one can therefore change the wheels over with no issues. OPC have quoted me under £100 for the complete assembly including new stem etc. I am investigating a service kit currently for around £20 that I think will do the job.

The link you sent looks very professional and I will follow that up.

From your note I take it you changed more than one sensor, was that because more than one failed, or were you recommended to change the set?

[Chris_in_the_UK]

Hi Allan

I changed them all - logic being that the car age was commensurate with a dead TPMS battery so the sensible thing was to change them all. The unit which sits inside the tyre is not serviceable - everything is sealed in potting gel.

The one's I got from the site I posted had the same Beru part number as my original Porsche items but (obviously) did not have the Porsche part number on them.