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If the TPWS light is on the tire pressure is below minimum. Make sure all the pressures are above 32 to 35 psi cold including the spare. Allot of the time with the cold weather people forget the spare and the colder the weather the lower the air pressure will be in a 20 degree tire. There is no reset switch. Once all the pressures are set turn the key on and in a few minutes the light will go out. If the light remains on there may be a bad sensor.
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