Then you've come to the right place. You wouldn't try to measure a 1.5v AAA battery on the 1000v scale; you'd get 001 or maybe 002, and what would that mean? You'd use the 20v scale, and you'd read something like 1.51. Same with resistance; use the lowest scale that doesn't give you "overrange." That gives you the most significant digits.

"mv" is millivolts, or thousandths of a volt. 2000mv is 2.000 volts.

An O2 sensor is an amazing gadget. http://www.cygnusx1.net/Media/Supra/...taTech/h37.pdf It's plated with zirconium dioxide, and when there is a difference in the oxygen content between the exhaust and the outside air, it generates a voltage! But it only works when it's hot (400°C), which is okay in the exhaust stream. Except when you're idling or rolling downhill or just starting. To get it up to temperature promptly most O2 sensors have an electrical heater. If that heater conks out, the ECU will tell you with a code.

Ah, probably not. Did you hold the test leads together? Did you get exactly 0.0 ohms? I'll bet you got something like 1.1 or 1.7; it also depends (slightly) on how hard you push them together. I'd say that 7.5 is "close enough" to 6.3. (If you really care I have a 6-digit lab meter with a "Kelvin" connection that's good at that level ... nah, you don't care that much.)

I gotta say I don't think it's your sensor; I think your problem is somewhere else. I just don't know where.

 

Would you look at leaking injectors? Is there a way to test that? Leaking cold start injector?

My only other suspicion is the ECT sensor being bad and keeping the ECU in open loop, or am I off base on that?

If it is the ECT, I'll need to verify with a picture which is which on that coolant bypass manifold. Every different site that sells those labels them all differently.