Mazda 3 Check Engine Light P0126 & P0128
The two codes from the check engine light are: P0126 & P0128
Here is what I found according to my research:
P0126 is either replace coolant temperature sensor or replace the thermostat. According to my research, 99% of the people who had this code needed to replace the thermostat. Once that was replaced, 99% of the people said that the light turned off and that they noticed the car ran better than it did before. Some people said that the repair is about $100 (including the parts and labor) and that no one should pay over $200. People said that they were even able to replace it themselves (if you can get under the car). The thermostat part is LF7015170. I looked it up online from a Mazda parts dealer and it's about $45-$50 depending on which parts dealer you buy it from. I'm sure I could even find it on eBay for cheap too.
P0128 indicates that the computer is detecting that the engine is not reaching operating temperature within a reasonable time after startup. I am guessing that this relates to the issue with the thermostat, but I'm not 100% sure.
CAN ANYONE GIVE ME MORE ADVICE/INFORMATION AS TO WHAT I SHOULD DO? HOW MUCH IT WILL COST?