I got this code when I checked the computer on my vehicle: "P0128". I looked up the code and it means "Coolant Temperature Below Thermostat Regulating Temperature". This code showed up about a week ago. I cleared it, and the vehicle actually passed inspection right after.
Later the same day, the Check Engine Light came on again, with the same P0128 code. My coolant level is just fine, so I apparently don't have any leaks. What might be causing the code? Thermostat perhaps?