exasemech

Just got a 2000 XJ. Someone removed the catalyst (and therefore the rear O2 sensor). I can replace all that but:


The check engine light "works"; it turns on if you create a misfire or unplug the fan relay BUT it is not normally on as it should be with no rear O2 sensor.


The bigger issue is that neither of my scan tools (no they are not from harbor freight) show the missing O2 sensor, nor do they show any (front or rear) O2 sensor voltages, coolant temp, VIN and other stuff they normally show. They also don't show ABS codes as they should ( the light is on). They did show the fan relay and misfire DTC's.


I suspect when the cat was removed someone did something to disable some of the OBD monitoring functions.


Any ideas?? Like cut wire xxx from the PCM or some other alley shop mod


Thanks

Cummins93

Typically cutting the signal to the pcm will result in a CEL. Are all wires to the obd port intact? Rear o2 signals can be fooled fairly easily. The front sensor should display a voltage even if the sensor is faulty. I assume you are using a live data function. Are you using an actron?

exasemech

C93


Thanks for the reply. I was using 2 scanners, and Innova because it does ABS and an older Auto-Xray 4000 to do the live data.


The Innova "connects" and will showed the misfire and fan faults I caused but does not show any systems (O2 for example being monitored and does not show an O2 sensor fault. It says the vehicle does not support ABS monitor scanning but the tool is supposed to work on 2000 Jeep and has worked on other brands.


I used the other scanner to look at live data. On this vehicle it DOES show throttle position but nothing else...on my 96 XJ it shows both O2 voltages, temp, throttle position etc..


I would like to sort this out so I can use the scanners for diag....it's tough to work on stuff without that capability.


Thanks again