[sashakoul]

If P0141 points to the heater circuit, you may have a few minutes of testing on a cold engine start to measure for 12v power to the heater circuit. As I understand two part O2 sensors, the heating element (similar to seat and steering wheel heaters) is powered up on a cold engine to accelerate sensor operation along with hot exhaust gases to minimize time in cold engine running with rich fuel mixtures. The O2 sensor needs to be heated above approximately 600F+ before it begins to output valid signals. On cold engine startup, open loop mode occurs with rich fuel mixtures. As coolant temps rise above a certain temperature and the O2 sensor reaches operating temps, closed loop mode occurs where tight emissions control regulates engine running to meet emissions requirements. Some EFI systems runs O2 sensor heaters for a few minutes then removes power. If 12v power isn't there at cold engine startup, the OBD II system detects an issue and pops the error code. Warm engines don't need the heater powered up since coolant temps tell the EFI system the engine's already close to operating temps for emissions control.

From what I’ve read, it sounds like the PCM only controls the ground for the heater component. So the positive wire should show a +12V reading at all times when measuring from a true ground (correct me if I’m wrong, I’m just regurgitating). If the PCM provides a ground for the circuit but doesn’t see a current flow, that’s when the code shows up. I would do what Nutjob says and measure cold, but check the voltage across both heater wires and also with respect to a solid ground, IF you don’t see power across both wires. That will at least narrow it down to being an issue on the negative side.