Originally Posted by
StevE55
No Change ~ Unplugged & removed both 3 & 4 (post cat), swapped, then reinstalled..
Same Lambda test in DAS, several 60 sec. test and even though #3 O2 sensor’s in # 4s place, #4 it still lays low until 1500+. Heater test passed, mv test showed 750Mv +/- for each and all seems to be functioning.
Maybe I’m overthinkin this but here if you fail emissions then it’s like a Scarlet letter, like what you went through…
I’ll apologize in advance if the pic is the size of a Drive-in theater (can’t seem to get it right)
The dotted line is #3 Rt-Aft & the line along the bottom is #4 Lt_Aft (at idle)
Hopefully someone with more knowledge of the O2's could chime in. I'm at a loss. It seems pretty weird.
You're using the stock rear O2 sensor plugs and wiring correct?