88 K5 O2 sensor getting low voltage

[Walks with Big Stick]

Hey all-
I have an 88 K5 350 engine and the O2 sensor is only getting .18v when the ignition is on (engine not running) and correct me if i'm wrong but shouldn't it be getting around .45v? I have replaced the ECM, routed the wire from sensor back to the ECM and no problems there. Bottom line, the truck failed emissions for running rich. I have replaced CTS, O2, ECM, spark plugs, spark plug wires, etc. What could be causing it to get only .18v? It will start up fine, but soon after starts to make popping sound from running rich, i assume. Any help is greatly appreciated

 

[Fordum]

OK, you have the wrong end of the stick.
The O2 sensor Generates voltage, it is not supplied with it except for heated ones. And they get 12 volts to the heater, and the output wires are the generated voltage by the sensor.

When the mixture is right, you get the .45 volts out. In your case, it does not matter, since the engine is not running.
.18 is a very lean mixture, which means that there is a lot of oxygen in the exhaust.
Since the engine is not running, there is no exhaust. So, since you are measuring the amount of oxygen in the air its self, its going to be really lean.