My 2000 4.0 has trouble codes for O2 sensors (P0131 B1S1, P0138 B1S2, and a lean code P0171) I am getting about 12mpg avg. I've been trying to find O2 sensors, but everywhere I've looked suggests there should be 4 total. I only have two complete O2 sensors and they in the same location as my buddy's '96 XJ. I attached a picture of two cut sensors on either half of the manifold. The scan tool image shows 4 different readings, with B2S2 actually having a reading that isn't pegged at either extreme. I've inquired in other forums about this issue and I was told someone had likely installed a manifold conforming to different emissions and left the sensors in to plug the holes. I have not been able to find any loose connectors or cut wires. I would like to know which sensors I'll need. I wanted to ask before I buy. Any input is greatly appreciated.

 

Yeah, that's wacky.

Here's a thread with a picture of what the California 2000MY emissions version (4sensors with 2 close coupled cats) looks like

https://www.cherokeeforum.com/f2/cal...cement-203823/

The federal version only has 2 sensors, one upstream, one downstream of one main cat.

No idea what you have going there. Just to get started see what emission label says, maybe look àt build sheet web site.

 

O2 sensors only have an output of 0 to 1 v. Anything higher means a shorted harness...probably to the heater wire when they cut the harness. if you take the heater relays out it should ignore the improper voltages, but with such a butcher job ...who knows what is really going on.

 

Sticker should be on driver side firewall:



but if your PCM is looking for 4 oxygen sensors you should have a California XJ.

Look on top for 4 oxygen sensor connectors and see what you got.

 

I think the manifold is fine, but the sensors aren't in the right holes and/or connected to the right sockets. Find the 4 plugs in the harness and see what's been MacGyvered.

 

That wasn't MacGyver, that was Jack the Ripper..