Downstream o2 sensor

[Goatxxmastr]

Hey guys, this is my first post on here. I did some searching but couldn't find any info except where the o2 sensor plug is located.

So, the problem... I just bought my car a week ago and it seems to run pretty well (besides the crappy acceleration) but the CEL light keeps kicking on for the downstream o2 sensor. If i reset the codes, it takes any where from 80-100 miles for it to turn back on. Is this normal for an o2 sensor to take this long to to pick up if its going bad? I'm not to worried since it doesn't mess with the engine at all and i'm used to seeing a CEL light on all the time (last car had one on all the time for a cracked egr pipe) but if it happens to be an easy fix that would be nice

 

[grothe3297venge]

Just replace it and it will go away . 1996 MITSUBISHI ECLIPSE Oxygen Sensor - only 40 bucks!

 

[necrotopsy]

Is your cat converter stock?

 

[Goatxxmastr]

I'm not sure if the cat is stock, im almost positive the muffler is after market, though a very basic one...i do plan on putting a full exhaust on it though including a test pipe. It will still have an o2 bung but... I'm pretty sure it will set the code off a lot though. I didn't really understand the instructions on how to bypass that sensor (no emissions where i'm at)

 

[rough]

You don't wan't to bypass the o2 sensor, it helps tells the ecm what's going on and what to do to keep you running properly. I had the same problem as you, would go sometimes a week, then it starting turning on more and more, then stayed on replaced it, never came back. Easy fix and you will get better MPG

 

[Goatxxmastr]

Isnt the downstream sensor just for letting me know if my cat is functioning properly? As far as i know, it has no effect on the air/fuel ratio

 

[cl1ckclack]

You don't wan't to bypass the o2 sensor, it helps tells the ecm what's going on and what to do to keep you running properly. I had the same problem as you, would go sometimes a week, then it starting turning on more and more, then stayed on replaced it, never came back. Easy fix and you will get better MPG

wrong, the downstream o2 is for emissions purposes only

Isnt the downstream sensor just for letting me know if my cat is functioning properly? As far as i know, it has no effect on the air/fuel ratio

correct. it doesnt come back on because it takes that long for all of your DTCs get ready

 

[Goatxxmastr]

I apologize, but what is a DTC?

Never mind, i found it.

 

[necrotopsy]

spark plug non-foulers.
buy 2 of them.
i don't remember the size... 5/16th maybe?

take one of the fouler's and drill out the middle of it enough that you can screw your 02 sensor into the spark plug non fouler. then screw the other (not drilled) non-fouler onto that one.
then screw the whole thing into your exhaust.

 

[Goatxxmastr]

Lol i love the drawing. What is this going to accomplish though?

 

[necrotopsy]

it removes the o2 sensor from the exhaust stream so therefore you can have a test pipe installed and it won't pop a CEL for cat inefficacy.

all the downstream 02 does is compare the numbers given from the upstream 02 and if the numbers aren't different enough, then the ECU knows there is a problem with the cat.

If you move the o2 sensor from the stream then the numbers will be a lot different. = no CEL

 

[Goatxxmastr]

Oh, you maka da sense now... Thanks for that

 

[bullettdsm]

it removes the o2 sensor from the exhaust stream so therefore you can have a test pipe installed and it won't pop a CEL for cat inefficacy.

all the downstream 02 does is compare the numbers given from the upstream 02 and if the numbers aren't different enough, then the ECU knows there is a problem with the cat.

If you move the o2 sensor from the stream then the numbers will be a lot different. = no CEL

Just so you know, while this is effective in some cars, in ours its hit or miss. Sometimes it works but oftentimes it doesn't.

As for your cel's, d1ckclack hit it on the head.

MB

 

[necrotopsy]

Just so you know, while this is effective in some cars, in ours its hit or miss. Sometimes it works but oftentimes it doesn't.

As for your cel's, d1ckclack hit it on the head.

MB

that's odd, i've personally seen it done on 3 420a's (two of them mine) and worked all 3 times.
an odbi 95, and a 97 and my current 98.