P0128 & P0303 - Check engine light on on 2003 Chrysler PT Cruiser

First occurrence of issue. Cold (15 degrees F) temperature start up - saw check engine light on - and has stayed on. Used scan tool to find two DTC's P0128 & P0303. Can you determne what is wrong just from this (& what I need to do to fix it)?

Asked by for the 2003 Chrysler PT Cruiser
P0128 is likely to be a stuck open cooling system thermostat or low coolant level. P0303 is a number three cylinder misfire, check the spark plug, fuel injector and connection or vacuum leak at number three cylinder.
Yes, very cold day in Jan the code appeared