In auto use I think it matters what maufacturer you are reading about, GM calls all of them O2 senors, others vary with AF sensor others have to spell every word out. David.
From: "Ernest Christley" <echristley@att.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Tuesday, February 12, 2013 9:38:22 AM
Subject: [FlyRotary] Re: Crickets & progress
That may well be the case. I am curious as to why that sensor is called out specifically as an air/fuel sensor as opposed to an O2 sensor, why the output is 0-5 V as opposed to the 0-1 V of a normal O2 sensor, why it has 4 wires instead of 5 or more for wide band sensors, and why it costs $200 or more depending on who is selling it. Of course, you doesn't always get what you pay for.
Some heating elements use current flow through or voltage drop across the heating element to determine temperature, don't they? That would explain the 4 vs 5 wire.