what are codes P0128 and P0171 for a 2001 Kia Sportage

Question

What do I need to have done or repaired when my car has these codes and could it pass a smog test before fixing these issues?

Answer 1

P0128 Thermostat stuck open

P0171 Sytem too lean

For P0128 replace the thermostat , as for P0171 this is a lean condition this can be from a vacuum leak to a contaminated MAF where a MAF (mass air flow) cleaning may help,you will also need to measure the fuel pressure the fuel pressure specification are at idle 38 psi