Hi guys.

So driving home on the back roads earlier i get a tyre pressure warning come up. Looks like 2 tyres both on the passenger side, at first i thought it was all 4!!

Thing is I've never set the tyre pressure set point in the car status menu but it still seems to be keeping an eye on them regardless which is to be expected i guess.

So I've been round all 4 and got them a 30 PSI (they all showed around 26.... my bad...) Will check a bit later if anything has dropped.

So if it turns out that i do indeed have 2 punctures and have to get it sorted whats the deal with the valves? I've never owned a car that had tyre pressure monitoring before!!

Would they need replacing like they normally used to do with old school valves when you had tyres changed?
How are those pressure sensing valves powered?
Whats the pressure window of values that trigger a drop? 1/2/3 PSI?

Cars in for its first service in the morning just to add to the chaos...

 

Cheers

Just standard tyres and valves and nothing on the wheels.

 

Enough of a drop in PSI / circumference of the tyres will trigger a change, it might be 4 psi it might be more.

Once you have the tyres sorted out you can experiment by setting the pressures, resetting the TPMS.  Then later drop a tyres pressure and see when you get a warning.

I see, that's good news for the wallet i guess!!
What does it use  / how does it measure things then? Some kind of sensor per wheel on the body work somewhere?
All 4 look like there still up and pretty much where i pumped then up to earlier. Temps have cooled off a bit now so might of dropped slightly.

The TPMS didn't trigger (yet) so like you say would have to be a few PSI to flag a warning.

Maybe they were a bit too low so the tyre deformed to much. 30 down to 26 would be the 4 PSI you mention if its clever enough to know that. I'm not sure that it is?
I've just read on a random kodiaq forum that it measures the rotational speed of each wheel, maybe using the ABS sensor?
It seems they had random triggering and couldn't find anything wrong. Reset TPMS and problem goes away.
Even talking about triggering on the difference between cold vs hot, but that would have to be a crazy change of PSI i would think!!
Just a bit unnerving it flashing while driving.

Hopefully all is well then, find out in the morning.... 

Cheers

Edited 6 September, 20205 yr by Gonzini

The system is an indirect tyre pressure monitoring system, so that means that it monitors the frequency of the ABS sensors on each wheel and flags a warning if one or two or three change.  This system needs to build up a data profile, so anytime you start experimenting by dropping the pressure of one,the warning will not normally be instant.

I had a warning on my wife's 2015 VW Polo last week, things "felt" okay so I continued until I could safely stop, got out and checked all four tyres and they looked and felt okay, so continued enjoying our day!

Next day I checked all the tyre pressures and the ones on the RHS were 0.5PSI lower than the ones on the LHS - but one side of the car was in shade and the other in bright sunlight, so all good.

 

I'm suggesting that you have had a "ghost" warning, it can happen, I've had a few false warnings with this car and my own, every time I've stopped and checked the tyres visually and checked the pressures as soon as convenient.

 

You show be checking all your tyre pressures once a week or at worse once a month, if adding any air then you must go into the TPMS section and reset it.

Edited 6 September, 20205 yr by rum4mo

Yeah I've been a bit rubbish checking the tyre pressures, totally my bad. I'm normally on the case but maybe not weekly,
It helps knowing how it works anyway.
Having looked into it a bit more i see those pressure sensing valves are still a thing again. Nice info to have but more to go wrong....

I know the car better after a year but I've not looked at all the functions available since i first got it. I just get in it and drive.

Best bit for me is the stereo, having all my music on tap off the USB is great with all the tagging / playlists and it plays FLAC's  
A few annoying things it does, like not being able to unlock the boot while the engines running being one. Unless there's a setting for that?
And i wish you could toggle the auto start / stop and it remember the preference.

Oh, and the rain pouring off the roof straight into the foot well when you open the door and get in it. It even does it with the window down, door trim gets soaked....

Just checking.

The monitor on the Fabia doesn't tell us which tyre has lost pressure does it?

I know some cars do.

It does if i interpreted the screen graphic correctly. It highlights which wheels have an issue (or not...!)
Mine came up with the passenger side, front / rear.

@Gonzini

Scary to think you collect a car and drive it with tyre pressures that someone you do not know set them too. But then many do just that.

I hope after the service you check what the pressures are for how your car is used and reset the TPMS then check the pressures regularly or at least as the seasons change.

The system works well as long as you know what you set it at yourself, weirdly I have had it work the other way when the tyre pressure went up (not down) one was an extremely hot day and spirited long uphill blast in the MK3. In the MK2 it was a sign of sticking caliper. Keep a separate tyre pressure monitor inside car. https://www.amazon.co.uk/dp/B07P5RG8TL/ref=cm_sw_r_cp_apa_i_EpEvFbGMH6EZY

Most cars use the indirect system as already described. They compare wheel rotation speeds and if one changes relative to where it was set. We had a couple of false warnings on our 2016, and it never showed which wheel. We now have a 2018, and it correctly showed which wheel was the problem, and had a small screw in it.

 

Some cars (and other vehicles like caravans) use a direct pressure method. This can be either with a sensor mounted inside the wheel, or for aftermarket a special valve cap.  The sensors send a signal to a receiver using a radio link. It has the advantage of being able to detect pressure loss more quickly (which is really important on high performance cars) or where there is no ABS sensor system (like caravans).

I had several "false alarms" with my Yeti but it always pays to check.

I set tyre pressures cold and reset the system before any long distance

towing, I think that the slight increase in tyre heat may have triggered the alarm

which was not wheel specific on the Yeti.

One occasion It threw up an alarm so I stopped off the road and inspected the tyres

I could see nothing wrong but I ran my hands around the inside of all the tyres and

encountered a screw head, no leak as such, I drove on at lower speed and got home

with no more alarms. The tyre fitter could not remove the screw so It was a new tyre.

On 07/09/2020 at 00:07, Gonzini said:

It does if i interpreted the screen graphic correctly. It highlights which wheels have an issue (or not...!)
Mine came up with the passenger side, front / rear.

 

I need to check my November 2018 Fabia again. I'm fairly certain it doesn't show which tyre has lost pressure.

36 minutes ago, RickW said:

 

I need to check my November 2018 Fabia again. I'm fairly certain it doesn't show which tyre has lost pressure.

 

If my 2017 model shows which tyre has lost pressure. Yours will also.

On 07/09/2020 at 07:40, e-Roottoot said:

@Gonzini

Scary to think you collect a car and drive it with tyre pressures that someone you do not know set them too. But then many do just that.

I hope after the service you check what the pressures are for how your car is used and reset the TPMS then check the pressures regularly or at least as the seasons change.

Yes you are 100% correct. Classic is when you've had a tyre repaired / replaced, they seem to pump them up really high.
I pumped all mine to 31PSI and reset the TPMS before i dropped it off for its first service yesterday. I will check them again, but i have bad knees and my backs gone today!!!! 

On 07/09/2020 at 08:44, Kobayashi said:

The system works well as long as you know what you set it at yourself, weirdly I have had it work the other way when the tyre pressure went up (not down) one was an extremely hot day and spirited long uphill blast in the MK3. In the MK2 it was a sign of sticking caliper. Keep a separate tyre pressure monitor inside car. https://www.amazon.co.uk/dp/B07P5RG8TL/ref=cm_sw_r_cp_apa_i_EpEvFbGMH6EZY

 

I've got 2 pressure gauges in the boot, for a sanity check as they're both cheapo jobs.

3 hours ago, RickW said:

 

I need to check my November 2018 Fabia again. I'm fairly certain it doesn't show which tyre has lost pressure.

 

Mines the 2019 SE L 1L 
Suppose the screen is a bit buried, under the car menu if i recall correctly. I think i had to get to it from the bottom selection tab and maybe cursor over to the next page.....