does a loose thermostat cause check engine light to appear? on 2000 Toyota Solara

i got my car serviced for valve cover gasket leak water pump and timing belt in one day. once i picked car up a few minutes down the road my check engine light was on. it was never on prior to being serviced. i stop by advanced auto. they tell me to look up code p0125 which says insufficient coolent temperature dealing with thermostat. since engine had to be removed and replaced for the above repair work prior to this, could it be that the thermostat is just loose?

Asked by for the 2000 Toyota Solara
no it won't
1 more answer
They most likely didn't get it (the sensor) plugged back in correctly. Bring it back and have them re-check and test drive again. Re-set the trip odo. to 0 so you know if they actually drive it. Cars should be test driven after any major repair (my opinion) to avoid situations like what you describe. Good luck.