P1126 Indicates that the Computer has not seen the coolant temperature rise enough given the amount of time the engine has been running. Chances are, the thermostat is stuck open. However it's possible that the coolant temp sensor has gone bad.
You need to determine the actual operating temp of the engine. If it's below 180*F, the t/stat's opening too soon.
9 year-old car?... Properly service the cooling system; replace the t/stat with a top-dollar after-market or, better still, an OE part; refill it with the correct coolant, at the correct mixture, using the correct procedure; clear the codes; recheck for any pending codes.