What happens if you connect a 3-wire o2 sensor backwards? The negative connected to the positive, vice/versa?

Question

Will the computer still see the O2 sensor but misread it or will it destroy the o2 sensor with prolonged use?

Answer 1

"Smoke Test"

Answer 2

the body of the O2 sensor is also grounded.  And so is the negative wire. So connect that to positive and you get a short circuit (and possibly burn out the computer).

===

Assuming your O2 sensor body is NOT grounded, then it will see negative voltage (but to a digital computer zero volt and anything less is still zero), and throw a bad O2 sensor CEL.

good luck...

Answer 3

I'm surprised you could hook it up backwards... :) The computer will just read the reference voltage backwards and set off a check engine light. Your engine will probably run rich and you should be having some drivability problems (if you have already hooked up the HO2S backwards).  

Answer 4

If you are lucky,only fuse is burnt,or worse,the ECM is fried,due to 12V battery feed directly to it.For this,do not use those universal O2 sensor that you have to cut and connect wires to mach the car's connector.Maybe it is too late since you are asking the question,good luck.