P0125 Lexus - in conjunction with p0171

Question

What could be the cause of a p0171 code in conjunction with a p0125 code in a Lexus is 200

Answer 1

P0125 Insufficient coolant temperature for closed loop operation

P0171 Fuel trim lean Bank 1

This is 2 seperate issue, P0125 the vehicle tend to run on the rich side,  the first repair should be with the thermostat  and the cooling system. the most common problem is the thermostat,

Here is a thermostat that caused a P0125, it stayed in the open position ,