tyre pressure alert
 

hmmmm, first time ive seen this, driving to work this morning the tyre alert goes off, red symbol on dash and tone.

so i stop get out and check the tyres, do the thumb pressure test, and all seemed ok.

got back in and started the car, warning light still on, so i pressed the button and held it for a couple of seconds, it went yellow and then went off, and the warning hasn't reappeared.

on my driveway at home the sun in the morning hits the right hand side of the car and the left hand side is in shade, and as we had a quite cool night i wonder if the tyre pressures went up on the side in the sun, and that variation, when compared with the cold tyres on the left hand side was enough to set it off ??.

another possibility is that i didn't realise that i was supposed to do a re initialisation once new tyre are fitted, so maybe that was it

any thoughts???/

Every time you set the tire pressures you need to re-initialize it.

Pavement temp and/or ambient temp and/or direct sun on one side and shade on the other can affect the alarm. Happens to me frequently as the weather turns - both in spring and fall. But don't ignore these false positives, it's always good to stop and check. Then reset as you did.

thanks for the info, as yet the light has not reappeared, so i think that was the problem

Thanks

There can be quite a bit of differential solar heating on black rubber between the sun and shaded sides. This is particularly true if you live in a cool, high altitude area like I do. The tire pressure monitor doesn't directly measure pressure like some other systems. Instead it monitors wheel and tire size through counting rotations. That's why you need to do a reset when placing new tires.