bigbernie

So I unplugged all the O2 sensors on my 02 GCL (4.0). Now I have to put them back. Does it matter which sensor goes to which plug? Down stream of course.

MonacaYankee

Upstream and downstream have different part numbers.

bigbernie

The upstream sensors were Easy to figure out. The connectors are different lengths and only reached the sensor it was meant for. The downstream, on the other hand aren't as easy to figure out.

Should I just try one position and switch if necessary?

Ralph77

I am going with that you can't hook up the wrong O2 sensor to the wrong connector on the engine harness.
Physically impossible.
They do stuff like this so during manufacturing nothing gets hooked up wrong.
I believe these to be the 2 downstream O2 sensors for your Jeep.

https://www.napaonline.com/en/p/NGO2...put=o2+sensors

https://www.napaonline.com/en/p/NGO2...put=o2+sensors

So look at the shots of the connectors.
See the little slots/keyways whatever they are called?
You could not get the wrong O2 sensor on the wrong connector if you tried.
Well you could but you would have to try real hard. LOL.

bigbernie

Lol. That's not what I meant. So yeah the order does matter. I hooked them back up and I got the plugs backwards. A quick switch and the check engine light went out. But thanks for any and all help.