I'd like to install 3-wire O2 Sensor and have power to it between 0 to ~180 degrees but no power >180 degrees. Has anyone seen a contrl switch that could be used 4 this?

 

Vader posted a schematic for powering the O2 heater using the purge control, I believe it was. Try searching the topic with his username.

 

Just purely out of curiousity, why would one want to do this?

 

My thought was that a 3-wire O2 sensor needs 12v to warm up but then once the car is warmed up to operating temperature why keep heating the O2 sensor? If a control switch is totally a waste then let me know.

 

The O2 sensor actually reaches 1 wire operating temp (600F) way before coolant reaches 180. You could switch it off sooner, but it's not neccesary. The O2 sensor was designed to be constantly heated. On top of this, it's not drawing much power at all. It's not like it costs your car performance to provide electricity. Once it's driving the alt, it'll be able to supply all the power its rated for while only taking one constant number of horsepower.

 

Thanks 4 helping me keep it simple