00 WJ 4.0 O2 Sensors

[NickMaul]

Fellas,

I thought I’d bring my problems here since I am a Jeep noob. My DD WJ 4.0 threw a CEL for

I went and bought 4 new O2 sensors since my Jeep has full retard California emissions.

I replace all four. Pull the cable on the battery to reset the CEL. I don’t recall what my O2 sensor were reading before, but this doesn’t seem right to me after replacing all four sensors (cruising 70 mph on the interstate.

The downstream sensor shouldn’t be jumping around right?

I also noticed the wiring harness to one of the downstream plugs is stripped and the wiring is exposed. I think I need to fix that.

When my app does a scan it tells me this

Did the precats take a dump or does all seem well? (No current CEL) I drive 50 miles a day so I don’t want the ECM to be all out of wack.


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[Jody Treadway]

If the downstream O2 sensor is flunctuating, you either have an exhaust leak between the sensor and cat or the cat itself is failed.
The flunctating signal indicates the outgoing exhaust is similar in condition to the incoming exhaust

 

[NickMaul]

If the downstream O2 sensor is flunctuating, you either have an exhaust leak between the sensor and cat or the cat itself is failed.
The flunctating signal indicates the outgoing exhaust is similar in condition to the incoming exhaust

Thanks Jody. I need to confirm which graph line is downstream Vs upstream. I currently have no CEL on but I’ll keep an eye on this.


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[Jody Treadway]

Just read the voltages for the downstream. If it (they) move more than approx 0.10 V, the cat is no beuno