[Don Plumley]

It's all making sense now (assuming the sensors are failed and not the heater circuits).

After I source the Sensors, I'll have to come up with a clever way to protect them in the engine compartment. And it is making sense to go ahead and buy new sensors, put those into the pre-cat circuit since that provides fuel mixture input, and use the working ones for the post-cat.

Ingo / Bill / Rick - many thanks for your help on this one.