I had the SES light come on got it checked and it was P0125 code - which means either my thermostat , temp. control sensor or low coolant. Coolant is fine, any Ideas on how to tell if I need a thermostat or temp control sensor? Heat blows hot but not super hot and temp gauge never gets above about a quarter of the way up the gauge, Just got the Expy so I 'm not sure how hot the temp gauge should be, Thanks in advance.