1999 qx4 with p0325, p0429, p0155

[InfiniteInfiniti]

From what I've searched and read so far I'm hoping that the p0155 (oxygen sensor bank 2 sensor 1) code is causing the others.

I believe I have a bad heated oxygen sensor. At least I'm hoping thats all it is. I plan to pick up a multimeter and do some testing tomorrow.

I understand how to check for 12v, and check the continuity between terminals on the o2 sensor connector, but when the repair manual states to test for continuity between the sensor terminal and ECM terminal I get lost.

Where can I locate the ECM connector harness? If I disconnect it to test do I have to do "learning procedures"?

Do you think this is causing my other codes?

I'm in a bit of a financial bind so I'd like to do this all my self if it's possible. But the knock sensor code scares me and I really hope I don't have a bad convertor because that means off to the shop without a doubt

I've always done most of the work on my vehicles with my dad in our decently equipped shop at home. Problem is I moved 6 hours away, have very limited tools, and this is my work truck. I just started working and I just need her to hold out.

Let me know what other info you may need. Sorry if I rambled and haven't searched enough, I'm a little tired but I tried to do due dilligence. Thanks for any input!

[InfiniteInfiniti]

Ok so I got a meter and did some tests today.

I have power, and when the engine is running and warm the readings are pretty much within range. It's supposed to be between .1 and .9 mA and for the most part neither sensor was getting much higher than .75 or so. One of them did drop below .1 fairly often though.

When checking ohm resistance between terminals I had 7.5 ohm for both sensors.

According to the haynes manual, if I did everything right, that means I need to replace the sensors. My question is could these sensors be causing other codes?

It makes sense that if the o2 sensor isn't working properly that can damage the cat converter. But can it also cause a knock sensor code?

Also, the truck is a 99 and I'm the second owner, so I don't know exactly how it's supposed to feel but it does seem a little "clogged". I had a ford ranger that had a cat problem before so I have a little experience with that. I could just be imagining it though after seeing the codes. The truck has decent power I just don't know precisely what to expect from the 3.3 V6. Do you think it's too late for the cat? Because I live in NC where yearly inspection is required so unfortunately cutting the bastard off isn't really an option, I'd have to replace it. I'm hoping if I get on the sensors relatively quickly it might save the cat.

Any help or input is greatly appreciated. Don't have much of a choice but to keep driving it for work so hopefully she'll last until I can get caught up and on track from this move and either repair or replace her.

[InfiniteInfiniti]

i see after further reading that the knock sensor code could have been there all along with no ses light. So most likely need to replace the sensors is my ultimate conclusion at this point. Will update if/when I swap the parts