O2 sensor

2002_stanGer · Feb 2, 2004

My service engine light went on, and I was told that when ran through the computer, My rear right O2 sensor is bad. Do I have to replace both of them, and where is a good place to get them? Is there something I should look for when purchasing them? I still have my stock H-pipe, but am thinking about switching to either a high flow X or off road X. Thnx in advance!

Firemanz · Feb 2, 2004

Screw the rear ones. I say go and get some MILS since you plan on getting a different mid-pipe anyway. They will simulate that a good one is there.

2002_stanGer · Feb 2, 2004

Firemanz said:
Screw the rear ones. I say go and get some MILS since you plan on getting a different mid-pipe anyway. They will simulate that a good one is there.

Actually i have MIL eliminators from my last off road h-pipe. Is the MIL messed up?

Firemanz · Feb 2, 2004

I would say so. It's supposed to simulate a good one being there. If it's malfunctioning it isn't simulating chit.

I personally don't have the MIL's, I had my rear O2's turned off when I got my dynotune.....

Are they DM MIL's?

TriBlkCobra · Feb 4, 2004

Please post what the code number is and then we will know how to proceed. Without that information its all just guess work. But the actual code number will tell me whats wrong.

2002_stanGer · Feb 4, 2004

TriBlkCobra said:
Please post what the code number is and then we will know how to proceed. Without that information its all just guess work. But the actual code number will tell me whats wrong.

I'll definitely try to get the code number, but I don't know who will do the computer test for free Thnx for the help guys! But one more question, even if the O2 sensor if bad, the MIL eliminators will say that it's ok to the computer? Then it must be MIL eliminators, correct?

TriBlkCobra · Feb 4, 2004

2002_stanGer said:
I'll definitely try to get the code number, but I don't know who will do the computer test for free Thnx for the help guys! But one more question, even if the O2 sensor if bad, the MIL eliminators will say that it's ok to the computer? Then it must be MIL eliminators, correct?

Incorrect. Mil Eliminators require a healthy functioning O2 sensor in order to do their job. Catalytic converters are basically mechanical low pass filters that provide oxygen storage in the exhaust. Mil Eliminators are electronic low pass filters that filter the healthy O2 sensor signal and make the computer low cat efficiency test for DTC P0420 and P0430 pass. Thats all Mil Eliminators do, prevent codes P0420 and P0430. Post the code number and we will know what to do. Autozone will generally pull the codes for free. Just write down the codes and post them back here.

COBRA_SVT_VERT · Feb 10, 2004

So would a p0141 and p0161 mean they are bad.

I've bench tested them and the voltage doesn't seem to be high enough, but I got my info on how to test from the SHO forum.

.6 when heated for 20 seconds and .9 when w/in 4 seconds of removing heat.

One registered .06 in 20 seconds and the other didn't register.

TriBlkCobra · Feb 10, 2004

P0141 and P0161 are O2 heater circuit fault codes, not the actual sensor itself but the heater element which helps it reach operating temp quicker. If you're getting both of these codes together you could have a fuse out. I'd have to look at a CD to be sure but both codes together sound like a fuse. I dont remember if the heater circuits are fused together for all 4 or on two circuits of 2 sensors each.

[edit] just checked the CD. on your 98 the fronts are fused together and the rears are fused together so both out together would look like a fuse to me.

COBRA_SVT_VERT · Feb 10, 2004

TriBlkCobra said:
P0141 and P0161 are O2 heater circuit fault codes, not the actual sensor itself but the heater element which helps it reach operating temp quicker. If you're getting both of these codes together you could have a fuse out. I'd have to look at a CD to be sure but both codes together sound like a fuse. I dont remember if the heater circuits are fused together for all 4 or on two circuits of 2 sensors each.

[edit] just checked the CD. on your 98 the fronts are fused together and the rears are fused together so both out together would look like a fuse to me.

Thanks TriBlk...

Where is that fuse?

Also, one of my o2s will only push .43 volts when heated. It's supposed to be .6 minimum. That's prolly gonna trip a MIL as well.

Might have to get a new one.

Thoughts?

Thanks,
EJ

athensoutkast · Feb 11, 2004

TriBlkCobra said:
[edit] just checked the CD. on your 98 the fronts are fused together and the rears are fused together so both out together would look like a fuse to me.

THANK YOU!! I've been banging my head against walls over this same type of thing.

TriBlkCobra · Feb 11, 2004

Well the owners manual for my 96 acutally breaks out whats on what circuit. On the CD for the 98 it doesnt look like they break it out as much. My 96 shows a fuse inside specifically for the HEGO (heated exhaust gas oxygen sensors) which would be for the heater circuit. Theres a bigger PCM fuse under the hood which shares HEGO also. And I'm pretty sure on my car the rears and fronts are fused differently because I had to solve this problem before. But according to both manuals, 96 and 98, they look wired similar. Apparently the schematics dont break out the fuses on the 96. There is a little note by a connection on my 96 CD that I cant read which may indicate separate fusing. Its not on the 98 CD either. So, I guess I cant give you an exact point to look for. But according to the 98 CD, there are 3 Ignition fuses under the hood and one in the car (the one labeled "constant control relay module") that feeds the PCM. On the other hand, I do now the manuals are WRONG on at least one fuse. The cigarette light is actually on the power seat labeled fus. So if you have a voltmeter todays fuses are very easy to test. If you look at the top of there are two metal contact points. Just put the leads of the voltmeter on there and measure the voltage. If the fuse is open it will read 12V. If its good it will read 0V. I'd do it with the car running to be sure and avoid any hot in run only circuits. Sorry I couldnt be of more help, good luck. But for both to go bad like that I still gotta think its a fuse.

COBRA_SVT_VERT · Feb 11, 2004

And to think...this could all be cut off by adding a chip.

Even the MIL elims can't work if the o2's aren't working properly...

TriBlkCobra · Feb 11, 2004

Yeah, but I gotta believe it will be an easy find. Just check the fuses, I did it the other day for exactly the same problem on a 99 (which has yet another completely different fuse box layout....)

COBRA_SVT_VERT · Feb 18, 2004

Further checking of the O2s via beanchtop testing told me they were both bad.

I replaced them and haven't had a problem since...no MIL after 300 miles of driving and passed emmisions check today.

TriBlkCobra · Feb 18, 2004

Wow thats pretty amazing that both O2 heaters went south together. I've never seen that one before. Is it possible you damaged them taking them out and transferring them to the other pipe? Believe it or not they're actually very sensitive to shock, IE whacking with a tool or something like that. Anyway, glad you got it fixed and sounds like you nailed it as after 300 miles those codes would have definately showed back up if the heaters were still open.

COBRA_SVT_VERT · Feb 18, 2004

TriBlkCobra said:
Wow thats pretty amazing that both O2 heaters went south together. I've never seen that one before. Is it possible you damaged them taking them out and transferring them to the other pipe? Believe it or not they're actually very sensitive to shock, IE whacking with a tool or something like that. Anyway, glad you got it fixed and sounds like you nailed it as after 300 miles those codes would have definately showed back up if the heaters were still open.

The previous owner had them in the pipe when I bought the car. I've had the code since I got it, so who knows how long they've been bad.

Glad to see the light gone now though...first time ever...

O2 sensor

2002_stanGer

Firemanz

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2002_stanGer

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