Methods and systems for monitoring engine coolant temperature sensors are described. In one embodiment, an expected engine coolant temperature may be determined based on the accumulated engine mass air flow. If the current engine coolant temperature is substantially different from the expected temperature, then an error signal may be generated. In one embodiment, the expected engine coolant temperature is compared to the actual engine coolant temperature if the engine coolant temperature has changed by a predetermined amount. In one embodiment, the expected engine coolant temperature is compared to the actual engine coolant temperature if the accumulated engine mass air flow is equal to or is greater than a predetermined value.