Earlier this year, I had my CEL come on on my '05 Mazda 3 due to P0128 (asked about here). I cleared the code, and it never came back. Six months later, I have the code P0126 come up and now I'm wondering if I should be replacing my thermostat or doing something else? And my follow up question will be - how do I actually do the replacement or other suggested task?
INFO: My engine temperature on my dashboard shows that it is below the range of temperatures when I start my car, and stays there until I start driving around 2 miles. It also doesn't get to the middle of the temperature range until I am at highway speeds.