My TPMS keeps flashing up sporadic warnings for different wheels randomly. The pressures are a little different - lowest is 31psi, highest 34 - but all within what I would have thought should be an acceptable range. Anyway, when I took it back to the dealer the first time this occurred (lowest was 33psi then) they pumped up all the tyres to 40psi (supposedly high speed pressure for XFR) and I didn't get any warnings. I did get a rubbish ride though, so dropped them back to 34psi and the sporadic warnings returned soon after.

From a google around, there is mention of 'normal' and 'heavy' load settings for the TPMS system, which can be specified under vehicle settings for a 2015MY XF. Should I have this option on a 2009 XFR? If not, how sensitive should the TPMS be to pressure variations (I'd read 26-28psi is usually the threshold for nominal 34psi), and how close do the wheels' pressures need to be to each other for the system to think everything's ok?

I don't want to faff around deflating tyres by 25% with ignition off and then re-inflating with ignition on, if there's some setting that says 40psi is my datum pressure.

 

What's the warning? Is it the tpms system fault warning or the low tyre pressure warning?

 

Refer to the tire and pressure plackard inside the drivers door jam for recommended pressure

 

It's the low pressure warning - it says low pressure on (e.g.) rear right despite rear right being at 34psi, which is the recommended pressure for the rears. It'll typically come on for a bit for 1 or more wheels, then go off after a few minutes before coming back on with (typically) a different combination of wheels. Today it was front left and right - front left was 31 psi, front right was 34.

Sorry - that wasn't my question, although I realise what I wrote originally was ambiguous. My question should have been: does the TPMS on the original XF have 2 settings ('normal' and 'heavy' load settings) that need to be manually switched via the vehicle settings menu? I believe the latest XF and the XE both have this somewhere in vehicle settings, but I didn't find it in the same place on my XFR (if it exists).

If there isn't any way to tell the system what datum to use, how does the system determine the difference between a tyre at 'normal' load setting vs one at high load that has lost 15% pressure? I think my problem may be that the tyres were all at 40psi and now they're running 31-34 psi, so the system thinks they've lost pressure. How do I tell it that 34 is my new datum, so it needn't bother me until the pressures drop below 28ish?

 

Have a look in the XF forum, I remember a thread where the guy set his pressures to 25 all round, started the car and let it idle for 15 minutes then switched off. Then inflated tyres to correct pressures and tried again.
He said, no more problems.

 

Yes that is the correct procedure if getting the check tire pressure warning,car running put tires to correct pressure,then switch off car for 15 minutes,after that go for a drive for at least 5 miles should be fixed,if not you have an issue with the tpm system faulty module/or sensors..

 

Just bear in mind that when I had a similar problem, the module under the front right seat never threw any fault codes, so it was hard to finally sort the problem. I fitted a new module and haven't had any warnings since and that's been a lots of miles driven.

 

i removed my tune to air to wireless my phone since then I have not had another light
all batteries were good and even had the module changed once never a code
had a buddy with a xf same thing

 

Silly question I know. Are you certain your pressure gauge is accurate? It wouldn't be the first time...

 

This right here!! I had the same issue with a USB charger plugged into the lighter socket, took it out and tossed it, all good.