OBDII P0125 trouble, celi is not passing emissions Options

[f1yen]

I had 4 codes, but got it down to 1.
P0125, insufficient coolant temp for closed loop fuel trim

So far I have new thermostat, new ECT.
When checking the o2 sensor (upstream), if it is unplugged and I check the voltage between the leads, My values are within range 0-1volt. so thats good.
When I hook the connector back together, and backprobe to get a voltage between the leads, i get a constant .5 milivolt....

I checked the wiring between the conectors and the diagnostics box, and from the connector to the ecu, to see if I had a low resistance > yes
Then I thought that maybe a wire is corroded or something that it cant handle the ammount of power through it... so I wired a direct line from the sensor output to just before the ecu. but same.

(for reference I also had a code for P0141 which is a faulty downstream o2 heater circuit, but i just hot wired some resistors to put the ecu at rest; at least for emissions)

Any help would be appreciated.

[Bitter]

have you checked that..
1. the thermostat is maintaining the proper engine temp?
2. the engine temp sensor is working correctly?

new doesn't mean its working right. also, the O2 sensor heater DOES help the sensor to read correctly, narrow band sensors need to be 400-600F to read right. try replacing the sensor.