97 Lexus LX450 P0125 diagnostic code

Indicates the ECT or CHT sensor has not achieved the required temperature level to enter closed loop operating conditions within a specified amount of time after starting the engine.

possible causes:
Insufficient warm up time
Low engine coolant level
Leaking or stuck open thermostat
Malfunctioning ECT sensor
Malfunctioning CHT sensor

Ray,
Getting infomation is such a PITA, and conflicting too. At work I checked alldata and according to that it points to your front oxygen sensor. I'm more inclined to go by this than my previous post.

I'm a service writer . what can I tell you?

[quote:27fa637540="rmunsch"]I'm working on a '97 Lexus LX450. I just replaced the engine after it failed the head gasket. Now it's showing a diagnostic code of "P0125...closed loop fuel system...insufficient coolant temp." I have replaced the thermostat & cancelled the code but after about two or three miles, the check engine light comes back on. Thanks, Ray[/quote:27fa637540]

Hey, Yeah one of toyota/lexus shining moments......code desciption points you in the wrong direction ....... O2 is the cause, and was damaged by coolant when the head gasket failed.

Chris