[fozworth]

Today i was on the motorway and my runflat warning light started to flash.i staopped at a services and checked the tyres and all seemed fine .I checked the presure but they were all a little low.but as im not using runflats should the light of come on?ive put air in them all and presses the runflat button and now its off again.so is that it.

[Fin]

Well the system works by measuring the speed of rotation of each tyre, relative to the other three. When one tyre deflates it rotates slower, so the system recognises this. Its only meant to pick up sudden deflations, not long term pressure loss. I've sometimes had my warning light come on after I've gone over a cats eye, and its slowed a tyre that had lower pressure enough to trigger the system. It turns out it was a slow puncture, but the cats eye set it off.

Even if you haven't got runflats it will measure the rotations of your wheels. Maybe you went over a cats eye changing lanes or exiting the motorway.

[Morri7]

I'm no expert but I think that the runflat sensor is linked to the ABS system or something that monitors the speed that all the wheels run at and when it detects a speed that is different from what the sensor was set at (when you press the reset button) the light comes on............I think! I might be completely wrong but this is why it still works with non runflats.

[fozworth]

Ok cheers i'll keep an eye on the tyres but they were all about 25psi so a little low but now there just over 32psi .