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The only thing you're going to need to replace is the air fuel ratio sensor which is located in the manifold by the radiator. Make sure that you use only a DENSO air fuel ratio sensor. That is bank two sensor one. Anytime you have these three codes in combination 90% of the time it's just a air fuel ratio sensor malfunction. The other two codes are set due to the malfunctioning air fuel ratio sensor. However as a good measure it is always a good idea to remove the mass airflow sensor and clean it with electrical contact cleaner and blow dry with compressed air. There is nothing wrong with the thermostat just ignore the P0125 code.Skyvisions