They do have a heater, as my previous post mentioned, but it's nowhere near powerful enough (by itself) to heat the O2 sensor element to the approx 600F it needs to be to operate.
It does speed up the warmup process, and prevents the O2 sensor from cooling too much at idle.
Brian
Originally posted by horseydug:
A supplementary question: I thought they had a built-in heater which simulates operating temp until manifold heats up?
