[Tippo]

Hi there

Checked online for dash symbols cause my manual is at home but still a bit confused as to what the (!) indicator means when it is red on the dash.

Mine came up today so can I assume if it is red then it is definately either a flat tyre (running on runflats btw) or just low preasure after a period of time, must admit I have not checked the preasures for over a month now so they could well be low. Will check them tonight when I get home in the meantime though I just need to know the following please:

Does this RED light come on if a certain preasure is reached or does it only come on if the tyre has totally no preasure at all so would be flat if it was non-runflat?

Also do you only get a Yellow (!) symbol if there a malfunction with the system itself?

Finally I read on the US forums that 06 models don't have TPMS is this true for the UK aswell? If so then what system do I have?

Cheers

[toxicnerve]

Tippo,

The TPMS system we have is shite in the UK. The way it works is my measuring the rolling radius of the wheel, when that decreases by a preset amount (due to pressure loss) it throws up the warning.

It doesn't measure absolute pressure AFIAK (which is the case in the US and possibly other regions too).

If the warning has come up it means the rolling radius has changed (for whatever reason). I would suggest checking your pressures (and topping up if required obviously) then reset the system so it is recalibrated.

If the warning comes pu again soon after then you have a puncture or a cracked alloy/are leaking air from somewhere....

[Tippo]

Hi mate

Many Thanks for the info, thinking about it now I did go over a small pothole type crack in the road 100 yards before it came on so that may have done sommat.

Will check them tonight, reset and see how it goes.

Cheers

[toxicnerve]

Yeah, once you reset it if it's fine for a while then I imagine it will be fine. However, if it comes on very quickly after you have checked your pressures/reset the system then you might have a problem.

You say you hit a pothole, it's entirely possible you lost some air in that impact. It might be worth checking your wheel for deformation/damage (could be a cracked rim etc).

[Tippo]

Couldn't notice anything earlier when I got to work but will have a good look tonight too.

It was not really a deep hole but you never know.

Cheers

[Tippo]

Turns out the drivers side rear was totally flat. The one wheel I am sure has not hit a ruddy pothole and yet it was flat. Could not see anything in the tyre itself so pumped it back up, reset the TPMS and will see what happens over the next couple of days.

No need to do any gym work tonight after using that foot pump.

[toxicnerve]

lol,

See what happens over the next couple of days. If the warning goes off again relatively quickly then I would say there's a problem that needs investigating.

[Tippo]

Just for info it turned out to be a naughty screw.

New tyre ordered and will be fitted tomorrow after work £100 all in which is not bad for a run flat I guess.

Bit relieved tbh after hearing these issues with cracked and buckled alloys.

[toxicnerve]

Strange that we were discussing this just the other day.

Left home for a meeting today and about half a mile up the road, my warning light came on!

Offside rear was down at 2.3Bar!! Reinflated with 12V compressor, reset the TPMS and done a 150 miles since and it's been fine! Fingers crossed I dont have a cracked wheel or a puncture!

[Em135eye]

I find cold temperatures make a big difference - my front had dropped by 2 PSI and my rears by almost 5! Exactly the same loss front and rear.

I tend to use garage inflators - I have a 12v compressor in the boot (Ring) but with the bootliner in place, it's a bit of a faff to get to!

[toxicnerve]

Mine was just the one rear that was down. All the others were fine. Suspect there might be an issue with that rear so I will keep an eye on it.

I didn't fancy driving onto the next garage as it's a couple of miles away. It was easier to pull over and inflate on a side road. Thankfully I was pretty close to home anyway so it wouldn't have been a total disaster if I had to go back and get the space saver spare etc...though I would have been late for my meeting!

[Em135eye]

When one goes it usually spells trouble. I had a slow flat in my old RFT (rear nearside) - the upside being I realised tread was getting low and changed the useless lumps of rubber for non RFTs.

When all go down the same amount, the TPMS doesn't pick it up - which is kind of obvious but slightly alarming!

[toxicnerve]

Well the problem we have in the UK is that the TPMS doesn't measure absolute pressure. It just looks at the rolling radius of the wheel. If they all go down sufficiently it would pick it up but I think the differential from when it was last reset to it triggering is quite large.

It's not a great system to be honest but it picked mine up this morning which saved me doing 150miles on a flat tyre!

I will keep an eye on my pressures (usually check before any long journey anyway) and in particular the offside rear (which is the one that went today).

Could be a puncture or a cracked wheel

[Em135eye]

I thought it monitored the potential difference in rolling radius/tyre speed? If all are the same, fine but if one goes down the speed of rotation will increase and set it off. If all reduce the same amount, the there's no difference so the TPMS remains off.

Never found out what my slow flat was caused by - got shot of them as quick as I could! Must have been the tyre as the rims are fine.

It's not the best system but an actual pressure monitoring device would sure cost more, weigh more and be prone to dirt and damage? At least the system used is pretty simple.

[toxicnerve]

I think they have absolute pressure monitors on our cars in the US...possibly on mainland Europe too???

[Em135eye]

Originally Posted by toxicnerve

I think they have absolute pressure monitors on our cars in the US...possibly on mainland Europe too???

Yes but they're all fat and retarded so who cares?

[Tippo]

Originally Posted by toxicnerve

Strange that we were discussing this just the other day.

Left home for a meeting today and about half a mile up the road, my warning light came on!

Offside rear was down at 2.3Bar!! Reinflated with 12V compressor, reset the TPMS and done a 150 miles since and it's been fine! Fingers crossed I dont have a cracked wheel or a puncture!

Spooky that! Good to know it works to a degree though I guess.

Btw Thanks for reminding me that I actually have a 12V compressor I bought years ago somewhere which I had totally forgot about! D'oh!

Ended up paying £100 all in for a new tyre and fitting which is not bad for a Conti Run flat I suppose. Also paid extra for them to take off the retarded outer rim clip on weights the dealer put on last September and balance the wheels with inside weights as you would normally expect to see.

ALSO I had full four wheel alignment done whilst it was in. Phew.

Needless to say driving back home it felt like a totally different car!