Q: Engine temp reads low 2005 Chevrolet Impala

Hello - there are a couple of possible problems here: the thermostat may not be working properly, or the coolant temperature sensor for the gauge is not working correctly. A malfunctioning thermostat could allow enough engine heat for heater operation, but not be allowing the engine to operate at proper engine temperature (195-210 degrees farenheit). Also, if the coolant temperature sensor (for the gauge) is malfunctioning, it may simply not be reporting the correct engine temperature (in the center of the gauge). I would recommend a cooling system inspection by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, give you an accurate assessment of damage and cost estimate for repairs.