How do I turn off the tire pressure warning light.

what about the spare tire?it has to have the correct pressure in it also!

The sensors in the tires have batteries that are now 6 years old. They will need to be checked by a tire shop/dealer to see which one isn't reporting. It costs around $120 a tire to replace the sensor. If you can live with it and remove the bulb or tape over the warning light if you want. Just keep checking the pressure manually.