# P0128 code - Thermostat



## Bondo (Dec 8, 2007)

> Would this be a possible cause for somewhat low mpg?


Ayuh,... It'll cause it to run very Rich....


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## ukrkoz (Dec 31, 2010)

mpg in general drops down winter time. 
1. engines run colder
2. takes more time for engine to warm up
3. cold engine = more gas used
4. outside colder air = more dense air = more O2 = more gas used
5. dreaded winter gas formulation = more gas used.


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