Check Engine Light Oxygen Sensor

[sloweclipse97]

So I have searched the forums but no one seems to have this same problem. I recently installed a catback exhaust on my car. I had to heat the oxygen senor to remove it and soon after the check engine light came on. I drove the car for a while like this then had the code read and sure enough it was for the oxygen sensor. I bought a universal bosch sensor from an auto parts store. Had the code cleared, and still had the same issue. Now my car bogs when hitting a certain rpm range and seems like it has no power. I then bought a denso sensor to try and it does the same thing. I still have the light and bogging. Could there be something wrong with the wiring or is it the sensors? I'm lost and can't seem to figure this out. Thanks for any help or ideas in advance.

[Fotowntalon]

Check your catalytic converter, almost sounds like it may be clogged. Not saying you did this (but I have never heard of having to heat up the O2 sensor to remove it) may just be a coincidence of this happening at the same time as what you have done.

[zcoh2gdsm]

rear o2 only checks to make sure the cat is working. if it's throwing a CEL even after the new sensor and you feel a power loss it could be making a lot of back pressure from a clogged cat.

[jayson427]

I just had to same problem I couldn't get my sensor out since it was rust welded shut. Luckily I had an aftermarket exhaust to install it. I did the universal plug and my car ran like crap so i got the right plug but still my car is bogging and no power . It sounds like a lawn mower but I have other issues that are a factor. when you did the o2 did you reset your computer? Get the code erased and reset the ecu and see if that helps.

[sloweclipse97]

Yes I had the code erased by a scan tool, then I disconnected the battery for an hour and still no luck, light comes back on after about 5 miles of driving.

[96' Eclipse GS]

What exactly is the code?

[jayson427]

Your sure you got a downstream o2 and not the upper? Every flange is tight with no leaks?

[sloweclipse97]

P0140 - 02 Sensor Circuit No Activity Detected (Bank 1 Sensor 2)

[jayson427]

was the other sensor you bought with a clip? Or did you wire it in to the sensor plug?

[NHerron]

Here is the code straight from the FSM 97-99'. As mentioned, the code does not effect drive-ability

I dig those fenders on your car by the way, goes good with the flow of the car IMO

[sloweclipse97]

Every sensor that I installed I had to wire into the existing plug. So the code says it shouldn't effect driveability, but I get this stutter or jerking sometimes. Could this be an entirely different issue. Thanks for all the info so far guys.

[jayson427]

Bosch/Oxygen Sensor (13407) | 1996 Mitsubishi Eclipse 4 Cylinders Y 2.0L MFI DOHC | AutoZone.com

thats the sensor you should have gotten. some reason mine did the same thing it shuttered and what not but after a few weeks it turned into misfires. im not sure if your case is the same but your describing the same problem i just delt with.

[zcoh2gdsm]

Originally Posted by sloweclipse97

Every sensor that I installed I had to wire into the existing plug. So the code says it shouldn't effect driveability, but I get this stutter or jerking sometimes. Could this be an entirely different issue. Thanks for all the info so far guys.

take off your downpipe and check the cat. if it's clogged it's time to replace it or run a test pipe with an o2 fouler on.

[jayson427]

o2 fouler? iv never heard of that. i just had the same issue as the op and i am running no cat or egr. someone told me without a egr that my fuel trims would be way out of wack? but i have an a/fx tuned ecu and im still stumped on it.

[NHerron]

DIY O2 Sensor Bypass / Spark Plug Non-Fouler Trick Installation (w/ pics) - Honda Civic Forum

Pretty ingenious I believe it works on our cars too

[jayson427]

wow so its just a spark plug fouler on the o2? thats pretty smart lol

[NHerron]

Yup I've seen it work on a few cars especially in Montana when we don't have emissions. It's either pull out the honeycomb or weld up a straight through pipe when/if cat goes bad

[zcoh2gdsm]

Originally Posted by jayson427

o2 fouler? iv never heard of that. i just had the same issue as the op and i am running no cat or egr. someone told me without a egr that my fuel trims would be way out of wack? but i have an a/fx tuned ecu and im still stumped on it.

take a spark plug non foulers. dremel 1 out completely and screw it into the other one, then screw the o2 sensor into it and install it into the o2 socket how you normally would. it just moves the o2 sensor out of the exhaust stream so it doesn't trip the CEL.

deleting your egr wont do anything to your fuel trims, all that does is take the unburned exhaust gases and cycle them back into the engine. deleting it only hurts your fuel economy by maybe 1-2mpg. nothing serious.

[sloweclipse97]

So the code I'm getting is saying the sensor isn't getting enough gases to give a reading, caused by the bad cat possibly?

[NHerron]

No sorry about that we got off track. Your code is electrical. Do you have a DVOM? Check the heater circuit in the sensor by testing for ohms. It should be under 2ohms (doublecheck me) and the computer seems to think its open (not connected)

How did the wires look when replacing the sensor?

[zcoh2gdsm]

Originally Posted by sloweclipse97

So the code I'm getting is saying the sensor isn't getting enough gases to give a reading, caused by the bad cat possibly?

no, the code is saying theres a circuit malfunction. it's a wiring problem. do what NHerron said and check the resistance with a volt meter. the o2 fouler would work if was a bad cat but in this situation it doesn't seem to be. you should still drop the downpipe and check the cat though just for reassurance.

[sloweclipse97]

I will try to check that with a volt meter tomorrow if it ever stops raining. I'm curious if getting rid of the code would cure the bogging I'm getting since it was stated this code wouldn't effect performance.

[nicks tsi]

they have those o2 foulers on stm.com for 8 bucks

[NHerron]

Yeah... and any regular parts store should have them in a pack of 2 as well

[sloweclipse97]

Last weekend I "gutted" my cat to eliminate that from the list of potential problems. Car continued to stutter and seem underpowered. Today I made my car do the "keydance", wrote down the numbers and I got a "21" code. Looking on 2gNT.com, this says its the upstream o2 sensor? I know on the scan tool I used before I could have swore it said bank 2 or downstream. Car is still running badly and is now smoking badly. Bad upstream o2 sensor causing car to run rich?

[NHerron]

Your front o2 sensor is bad, replace time! It controls fueling so when it goes bad it makes car run in open loop all the time and you'll get terrible fuel milage/performance