TPMS learn mode - Help please

[OhmDr]

We just purchased a 2008 Aveo5 and the TPMS light is on. The seller told us the light just came on when it started to get cold. Since all of the tires are set to the proper pressure, I am assuming one of the following is true:
1) One or more sensors is going/has gone bad.
2) The tires were rotated and the relearn sequence wasn't performed.

My question is: How can I put the car into the TPMS relearn mode and do I need a relearn tool to put up next to each tire to TX the signal back to the receiver and "teach" which tire is which. That would also tell me which sensor(s) aren't working, if the TX signal isn't received.

Thanks.

[EAD15]

Assuming the TPMS sensors were never changed, at least one TPMS sensor battery is probably dead. Coming on when it started getting cold makes sense in that context too. My research suggested they are good for about 10 years and at least 1 of mine died around the 10 year mark too.

I'm just waiting for my next tire change before I replace them

[gclark8]

TPMS warning on cold mornings means you are close to the minimum warning threshold and pressure.

Most TPMS systems use ambient temperature at sea level for setting pressures (and not ISA) so it will be a pressure chasing game if you want a soft ride.

I agree with EAD15 on the batteries, a new set may be overdue.