TPC Inactive

[yan]

Whilst on a recent trip the console beeped up "TPC Inactive" (Type Pressure Control). I had noticed prior to this no reading on the right rear and called in at a local OPC to see what could be done. They diagnosed a dead sensor in right rear but were unable to resolve it there and then. The other 3 sensors reported 24months left of battery life. They kindly provided a quote suggesting that it would take no more than an hour.

What needs to be done:
1. acquire replacement sensor (the battery can not be replaced as the sensors are sealed units. A sensor costs ~£100 (before VAT, discount).
2. Remove tyre at least in part to replace sensor (part of valve).
3. The sensor needs to be programmed into the car so that the vehicle can pick it up (wireless connectivity).

On returning home I called my local PC who advised they would need the car preferably for the day! The reason being that in their experience part 3 can take some time for the car to recognise the new sensor. The process of the sensor being picked up involves driving the car around.

Rather surprised by this advice, vs original OPC, I phoned another local OPC who advised that it was not unlikely that I would have to replace ALL 4 sensors as Porsche had changed the parts at some stage and it was possible that my vehicle may be affected. They would not be able to tell until they got the vehicle in though, i.e. could not tell via the chassis number etc. And here was me thinking Porsche had an obligation to provide spare parts for some period after homologating a vehicle"¦ This OPC is confident the job certainly should take less than an hour and they had no experience of problems with the sensor being picked up by the car.

SO in light of rather conflicting advice and also that no OPC seems to do a Nitrogen fill I was thinking I would rather acquire the sensor myself, take it to my friendly tyre fitter to replace the sensor and finally pay an OPC to type in a bar code via the PIWIS, drive away and let the vehicle pick up the sensor in my time, not that of the OPC.

Does anyone have any experience of replacing tyre pressure sensors, i.e. do I need to be prepared for the hassle and/or cost that either OPC has suggested?

For what it's worth the sensors last on average 5yrs so if you have a >5yr old 997 expect this to snag to occur in the none-too-distant"¦ All-in-all a fairly badly designed piece of kit it might seem although I am not sure it is anything particular to a Porsche"¦

 

[Brian RS]

Interesting - just wondering if I will bother to replace just one when the time comes.
You will still presumably know the condition of three out of four tyres - better than the old days.

 

[garyw]

Mine are coming up to six years old, I guess I'd better start looking at getting them replaced.. another reason to sell the car []

garyw

 

[yan]

ORIGINAL: Brian RS

You will still presumably know the condition of three out of four tyres - better than the old days.

Afraid not, at least not on the Gen I: it renders all output invalid! All you get is a beep on ignition + red dash (!) reminding you there is a snag which I don't think you can turn off without a visit to the OPC...

I discovered a screw in a tyre on a previous vehicle due to an alert so consider it a useful feature to get fixed, although the design/cost/effort is surprising.

I read somewhere that all newly homologated vehicles will have to have TPM fitted from the end of this year.

 

[keithpms]

After 4 months of over wintering in the garage (car not me) I took the "old" girl out for a blast yesterday only to discover a "TPC Inactive" warning on the dash display. A bit of fiddling with the stalk resulted in no pressure readings for the nearside front and rear, but readings for the offside front and rear.

Does anyone know if there is an easy reset process that I can try before resorting to the OPC?

If the sensors have failed on two wheels/tyres, would all four need replacing?

Are failed sensors covered by Porsche's expended warranty, or are they deliberately designed with a circa 5 - 6 year life expectancy so that they can be classed as disposables and thus keep the OPCs in business?

The "old" girl is a Gen1 turbo of 5.75 years vintage and around 24.5k on the clock.

 

[Lancerlot]

The tyre pressure monitoring system is covered under extended warranty if it has an electronic fault, but if it stops working because the battery is exhausted, this is a wear and tear item and not covered. Battery life can be checked with the PIWIS tester in actual values.

If the sensors are replaced a Porsche Centre can calibrate the system because new sensors come with a code. However, if they've been fitted independently the system will self-calibrate after around 20 miles and/or 30 minutes. You have to set the function in the instrument cluster - it will say TPM learning.

The sensors can be replaced individually. If a vehicle has some sort of radar/speed camera system fitted, this has been known to interfere with the TPM sensors and cause the fault you are talking about.

Regards,

Clive.

 

[keithpms]

Many thanks Clive. I'll unplug the radar detector and see if that makes a difference (although I suspect not as its been on the car since new).

I will have to call in at my OPC and see what they say. Can the system be switched off temporarily so that I don't have to look at the constant warning signs? Does that have to be done by the OPC with their kit?

 

[Geoff_Fields]

Cheap alternative replacements here but quoted battery life only 2 years.
http://www.ebay.co.uk/itm/TPMS-OE-REPLACEMENT-TIRE-SENSOR-Audi-Porsche-Volkswagen-Phaeton-Free-Ship-1-/150985174626?pt=UK_Cars_Parts_Vehicles_Wheels_tyre_Trims_Trims_ET&hash=item23276aee62

 

[Lancerlot]

Coming from Taiwan, you may also have to pay UK importation duties on delivery . []

Regards,

Clive.

 

[lamboman]

useful information from PH:

http://www.pistonheads.com/gassing/topic.asp?h=0&f=48&t=1252652&mid=150197&nmt=TPC+Inactive+%2D+intermittent

 

[911 turbo newbie]

i got pissed off when the system kept going off when even the smallest amount of air had gone out of one of the tyres, got my indy to remove system from coming on, now just fill up at home with air, check weekly job done and no more warnings on the dashboard, also you can run tyres at whatever pressure you like, not what porsche want you to run,which i feel is far to much.

 

[keithpms]

Many thanks to you all for the responses. £400 - £700 for all four replacing does seem steep for something that I have never yet had to "use". If I could switch the system off and leave it off I would, because I also check pressures at the wheel on a regular basis.

 

[garyw]

The fact you've never had to use it is a bonus and really as I see it part of the system working.
Mine saved me from being sat in the middle of the Peak district waiting for a tow truck after it did work and showed a warning that I'd got a slow deflation from a nail in the tyre, this gave me a chance to get to a garage and replenish the air sufficient to get back home and the repair done- without actually wrecking the tyre in the process- thus £350 saved! (rear tyre)
The fact that I was actually having some great fun and using the car to its potential -with what could have been a flat tyre before I'd known anything about it!! shows how important the system actually working is and how it could have ended very differently.[&:]

garyw

 

[chrisH]

Anyone know if the TPM system fitted to the 991/981 series is any different in design with respect to needing batteries replaced every few years which are not coverd by warranty, extended or manufacturer's?

 

[keithpms]

Gary, okay you've convinced me [] ..... (although you could buy two new rear tyres for the price of four sensors).

Whilst I have your ear, should I now be regretting not following through my order for the McLaren 12C (having been concerned about the build quality of the prototype/early display cars and practicality as a GT)? Have you posted a user report/comparison of 12C v 997TT anywhere?

 

[tscaptain]

ORIGINAL: keithpms

Gary, okay you've convinced me [] ..... (although you could buy two new rear tyres for the price of four sensors).

Like Gary I had a nail through a rear tyre which gave a slow,steady leak while I was batting down the motorway. I was very grateful for the early warning before the the tyre, potentially, let go and I might have had a bigger bill than just two new tyres...........[&:]

Also as it is becoming law to have them fitted to new cars
http://www.itv.com/news/central/2012-11-01/new-regulations-for-midlands-motorists-as-the-tyre-pressure-monitoring-system-is-introduced/

(I presume for all motorists not just those in the Midlands!![])
then it seems a bit odd to want to disable or remove them from the car.

I'm also wondering how much lower than Porsche recommended pressures our poster above runs his car. I have a feeling they recommend those pressures for a reason and underinflated tyres are not good news either.......

 

[garyw]

Keith... you should should be kicking yourself heavily [] - although you've probably saved yourself more money with what they have lost over the first year [:'(]
I've not done a comparison report but have spoken generally about the usability of the 997 way above the 12C, things so petty like a glove box now seem so important!! []
The 997 Turbo seems to have an urgency that this one doesn't but upon glancing at the speedo you realise it somehow disguises it! I did/do love that grunt the Porsche Turbo gives, and it does feel so quick. However stick go-kart handling on the Turbo and your in a close place [8D]

I have tyre monitors on this, not just pressure but temp also [&:], great but the 911 is just so easy to view its readings, I don't even bother looking at them any longer- but know that it would warn me in advance of anything happening.
Losing a tyre would be a cheap option, like Alan mentions having a flat on what is a 100K Porsche supercar doesn't bear thinking about.

Another savour of the TPC was in Germany when Tom got a puncture and we were able to stop in advance of the tyre being wrecked, thus able to put the repair fluid in and Tom was able to make his way to the local dealer to get a tyre fitted, OK he could have waited for a few hours for a low loader to eventually arrive but at the time we were on an excellent section of tarmac and again I look at it as a safe result.