How can you tell an O2 Sensor is bad?

[Road-Rocket]

Didn't know where to post this. So here I go. In the last month the performance of my gst has declined dramatically. It feels very slow and gas milage has gone down the drain too. A full tank of gas would last me 1 week just from daily driving to work and the usual cruising around town on the weekends. Now it barely lasts 4 days with the same type of daily driving. I also noticed that my autometer a/f gauge doesn't work anymore. None of the leds light up. Then the CEL went on pretty much at the same time the a/f gauge stoped working. Could this mean my o2 sensor is gone? What are some of the steps I should follow to find out what's wrong with the gst? Any help will be greatly appreciated.

 

[Quasimondo]

At cruising speeds (between 50-70 mph) your a/f gauge should be constantly cycling back and forth between rich and lean. It should be doing this very quickly. If it's not cycling, or doing it very sluggishly, then your oxygen sensor may be suspect.

An easier thing to do would buy an obd2 code-reader and check the code. That will tell you which oxygen sensor is going bad or if there is another problem that's triggering the CEL and making your engine run so poorly.

 

[Road-Rocket]

None of the leds in the a/f gauge light up at all. Doesn't matter if I'm cruising in the highway or in the city. I'm going to go to autozone tomorrow see if they can pull the codes for me. Now, I've never done this before. When I get the codes, will it actually pop up on the screen what the problem is? or will it just show a code in numbers and letters that I will have to find out what it means? I'm hoping I can solve this issue soon. I got a bunch of performance parts waiting to go in including a brand new fp evo 16g turbo. Thanks for the info.

 

[daren_p]

Not 100% sure with these cars (I have dsmlink to check the cel codes) but usually you get the code and a brief description. I would think from what you are saying it is more then likely the front O2 sensor.

 

[-red97rum-]

None of the leds in the a/f gauge light up at all. Doesn't matter if I'm cruising in the highway or in the city. I'm going to go to autozone tomorrow see if they can pull the codes for me. Now, I've never done this before. When I get the codes, will it actually pop up on the screen what the problem is? or will it just show a code in numbers and letters that I will have to find out what it means? I'm hoping I can solve this issue soon. I got a bunch of performance parts waiting to go in including a brand new fp evo 16g turbo. Thanks for the info.

I'm pretty sure all those scan tools provide a short description of the problem. All the one's I've used at least.

Dustin

 

[Quasimondo]

None of the leds in the a/f gauge light up at all. Doesn't matter if I'm cruising in the highway or in the city. I'm going to go to autozone tomorrow see if they can pull the codes for me. Now, I've never done this before. When I get the codes, will it actually pop up on the screen what the problem is? or will it just show a code in numbers and letters that I will have to find out what it means? I'm hoping I can solve this issue soon. I got a bunch of performance parts waiting to go in including a brand new fp evo 16g turbo. Thanks for the info.

Diagnostic trouble codes are read in a PXXXX format. Depending on the quality of the reader they use, they'll either just spit out the code and the autozone technician will look it up for you, or it'll give you the code definition right there. In the event that they are at a loss to what code is, write it down and post it here. I have a DTC lookup program that has the code definitions.

 

[SexyGsX]

I upgraded my turbo to a 16G and after install my front 02 sensor started throwing a cel, i replaced the o2 sensor and now everthing is fine. what i dont understand is why after the install does it start the cel. when i removed it, i just wiped it with a dry rag and used nothing. i was very careful and all wires were fine. it didn't throw a cel before, i am just wondering how this could happen if i didnt do anything to it, i just replaced the turbo. any info would be appreciated, please and thanks!

 

[Road-Rocket]

I put some wrench time on my car today. The valve cover was leaking so I replaced the gaskets and installed new spark plugs. While in there I played around with the o2 sensor cable and noticed that the cable that attaches to it from the a/f gauge was not properly connected. That's why the a/f wasn't working. I also did a boost leak test while in there and found 2 major leaks. That would explain my crappy gas milage. When I started noticing all this issues, I had just replaced the 1g bov with a used Greddy Type S one. Well, the type s is leaking like crazy. I tightened the spring all the way and it would still leak. So I went ahead and put the 1g bov back. The other major leak is at the throttle body. I have a dejon i/c pipe and as you all know, the flange is paper thin. Well it's warped. I tried to take it out since I have a hahn pipe with a thicker flange available for replacement. However one of the nuts circled in green in the pic, wont come out. It doesn't matter which way I turn it. It just won't come out at all. It rotates but it just stays there. While trying to get it out, I got fustraded and ended up warping the flange even more. So the leak has gotten worse. I have no idea what to do about it. I'm going to try to remove the entire stud see if I have any luck. I just don't have the tools right now for that. In the mean time, I placed a secondary nut in there (you can see it in the pic) just to keep it as tight as possible. I still have to get it scanned for the cel issues though. This sucks. I have a ported SBR manifold, a brand new ported FP evo 16g, and a tubular o2 housing ready to go in. But I can't do anything until I fix all this other issues. If I'm unable to get that nut out, I'll just take the car to a mechanic and see if they have better luck.

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[drk mrk iv]

I believe they sell something along the lines of a nut remover at homedepot. It grips the nut and somehow breaks it or removes it. You might want to give that a try or at least look into it.

 

[Road-Rocket]

I believe they sell something along the lines of a nut remover at homedepot. It grips the nut and somehow breaks it or removes it. You might want to give that a try or at least look into it.

Thanks, I will definately look into it. I don't want to take my car to the shop, but if I have to, I will. Hopefully I can fix it my self.

 

[Road-Rocket]

I was thinking of just removing the entire stud. Will the double nut technique work here just like the exhaust mani studs? I'm at work right now, as soon as I get back home I'm going to give it a try.

By the way, I ordered a new o2 sensor which I'll be installing along with my new turbo, mani, and tubular o2 housing.

 

[Wufei]

The double nut technique should work with any studs. What it does is lock the 2 nuts together so you kind of have a bolt