How do you repair a 2000 Kia Sportage P0137 autoscanner code?

Answer 1

po137 is o2 sensor circuit low volts (bank 1 sensor 2)

in English means o2 sensor is not seeing the right temperature thru the catalytic converter. problem could be the o2 sensor itself, but more than likely it is the catylitic converter showing age. try replacing the o2 sensor first,remember there is 2 of them,one before the cat and one after the cat. so double your pleasure double your fun, rule is if one o2 is going bad ... then try a new cat.