I have a 95 NT 420A engine. Actually I have 2 of the same Eclipses. The manual states there are two oxygen sensors.
I can't find the downstream sensor on either car---it should be after the catalytic converter.
Did the '95's only have one oxygen sensor????

do they both have the stock cat backs?

I believe so. In between the exhaust header and the catalytic was the O2 sensor. Between the cat and the muffler is the resonator, and I don't see the 2nd O2 sensor anywhere on either car.

yes, there will be one on the down pipe, and one one before the resonator on the cat back, its there, 95's came with two, if you find the port where one should be and its closed up, you will probably have a CEL, that or someone took it out, along with the bulb for the CEL, but I bet its there.

When you say on the cat back, exactly what do you mean?

I don't get any CEL or either car and I know the CEL works on both since I get it to come on by removing some of the other sensors on the engine.

Cat back refears to the catalytic converter, and back. Find the cat and comb your fingers down the pipe till you find it.

It should be on the pipe between the cat and resonator----that's where the manual shows a drawing of it.
I didn't see it on either car, but I'll check again.

If i'm not mistaken, the wiring for the rear o2 on the 95's comes out under the driver's seat. Look for that wire and it should lead you to the prize.