P0125 Code Still On

Hey everyone, this is my first post here on Tacoma World. I have a ‘95 4wd 2.7L 5spd regular cab that I have fully restored (I’m going to post about it soon)

Anyway, I’ve got a p0125 code that will not seem to go away. I have replaced the ECT sensor located on the back of the engine block and the bank 1 o2 sensor pre-cat. Thermostat seems fine as the heater and temp gauge work great. Truck runs perfectly fine and seems normal, but the light keeps coming back on. I’ve heard that it can be as simple as just a vacuum leak or a loose wire. Anyone have any ideas?

 

Circuit Description [ ENGINE CONTROLS - TESTS W/CODES - 2.7L : DIAGNOSTIC TESTING : CODE P0125 - INSUFFICIENT COOLANT TEMPERATURE FOR CLOSED LOOP FUEL CONTROL ]
The oxygen sensor monitors exhaust gas oxygen content and delivers an input signal to ECM. The ECM uses input signal to determine fuel injection system operation. Sensors include heater. Code is set when sensor does not output a rich condition (0.45v or more) once engine is at normal operating temperature, engine speed of 1500 RPM or more, and vehicle speed is at least 25 MPH for at least 2 minutes.

Possible causes are:
Open or short in the sensor signal circuit.
Open in the sensor ground circuit.
Open in the sensor heater power or ground circuit (Although this should set a P0135 or P0141).
Excessive lean condition.
Faulty oxygen sensor.
Failing PCM.

I'd start with scan data and see what both sensors are actually doing, if one or both are stuck at 0v all the time verify there are no opens or shorts in the wiring between the O2 sensors and PCM.