which one of them oxygen sensors is the culprit?

[ghettosled]

"clogged catalytic converter" was diagnosed after plugging in a diagnostic scanner. the car drives fine, no rattle coming from the cat, and the motor seems to breath just fine at high rpm. so which oxygen sensor would give off this warning? i would hate to buy the wrong sensor, assuming it is the sensor.

[GrkBallaG]

I dont think its the sensor. The job of the cat is to trap oxygen molecules when the engine is lean and to give off the oxygen molecules when the engine is rich. So if you get the code clogged convertor, then i really dont think its doing its job properly and your releasing bad things into the atmosphere, just my .02 cents though.

[BadChicken]

what was the code?

[ghettosled]

unfortunately i dont know what the code is, the screen on the diagnostic reader just said something along the lines of "catalytic inop" or "catalytic non functioning." the parts shop dude said that translates to the cat being blocked up. can cat get blocked up but still appear to run fine? arent there 2 oxygen sensors - one that measures the fuel:air ratio and the other to monitor the cat? the car runs fine, gas mileage is good, everything appears to run as it should except for this check engine light being on. is there a way to test the sensor(s) with a miltimeter? any suggestions as what the problem might be? any suggestion or tip is much appreciated.

[ghettosled]

bump.

bueller... bueller...

[Mike Gerber]

Having more information about the car would be a big help. Year, engine and mileage to begin with and any maintainence that was done to the car and at what mileage. Also, as mentioned above, we need to know the code. If it's an OBD2 car, the code is specific to specific oxygen sensors. Example: P0135 is bank1 sensor 1 (the one in front on a 4 cylinder); P0136 is bank 1 sensor 2 (the one after the cat converter). If it isn't too far, I would go back to the auto parts store and have them check it again and give you the actual code. Then report back here with the code and someone will be able to help you.

Mike

[mspringer]

I agree with the above post - you need the actual code to know for sure. Autozone will read it for free.

An educated guess would be that the second O2 sensor is reading out of spec.
Most o2 sensors I have bought are around $30 or so, so its not a bid geal to do both, and they are supposed to be changed periodically.

However, a bad cat could contaminate the downstream (second) o2 sensor, so I would have a muffler shop give you an opinion on the cat. They are around $150 for a good one.

[BadChicken]

most likely it will be a p0420 code and you'll have to replace the cat, but you can have it tested at the dealership to be sure

[ghettosled]

thanks for the info. ill find out the code and report back. just for reference, its a 96, 4-banger, 105k miles and i replaced the pcv valve several days before the check engine light appeared.

mspringer - the dealer quoted me $140 for a new rear o2 sensor. are generics that much cheaper but work as well as oem (aside from a simple splice job)?

thank you so far!

[mspringer]

Ghettosled,
Generics are a lot cheaper, and are fine, in my opinion, they are all likely made by Bosch, anyway (dealer or generic). I have used universals and I have never had problems, and you are right - one splice is all you need - I usually cut off the factory pigtail and crimp that to the new (universal) one.

I do apologize, though, because my pricing is off quite a bit. Either O2 sensors have gone up in price, or I remember wrong...

I checked with O-Riley's - $62.99 for a Bosch universal.
Autozone (online) shows a Denzo universal for $61.99 and an Arvin brand (never hear of it) for $31.99, and a different Arvin for $35.99.

For $31.99, I'd be tempted to try the Arvin.

[Mike Gerber]

A 96 model will be OBD2, so there will be specific Oxygen sensor codes as I described above, if it is one of the O2 sensors throwing a code. The code will be either P0135 or P0136 as I described above.

Your O2 sensors are mostly likely 4 wire sensors (heated O2 sensors), so there will be 4 wires to match up and splice. I think somebody mentioned 1 wire to splice. The older sensors were just 1 wire. My 94 has the 1 wire sensors, but most OBD2 cars have the 4 wire sensors. When my rear sensor went out on my 98 I stuck with OEM, although it was a bit pricey at $135 plus tax. It was turning cold outside and I didn't want to spend any more time outside than was necessary. Splicing 4 wires was not in my plan. Just for information purposes, I believe the Toyota OEM O2 sensor is made by Denso, but I am not certain. Which way you go is your choice.

Mike

[ghettosled]

i ran out and bought a generic code reader. the code thats being read is 0420 which translates to "catalyst system efficiency below threshold (bank 1)." anyone got a translation into layman's terms??

[BadChicken]

please read my previous post

[ghettosled]

oops... thanks badchicken.

[hooRAH]

Ghettosled,

I've actually just been dealing with this problem with my Dad's 98 Accord. Same code, about the same mileage. I replaced the sensor with an OEM denso from BMAParts.com (best prices I've found), it was like $65 (no splicing required). I suppose I could have gone with the universal and spliced it, but its not my money

Code came back, so I guess the O2 sensor was not the culprit. Now, I don't want to mislead you by saying that your situation is exactly the same, (and don't give me crap about Hondas and Toyotas being different, a cat converter is a cat converter), but I think that replacing the rear O2 sensor might be wasting money. At the very least, if you want to replace it anyway, it will save you the hassle of having a shop tell you "its the O2 sensor" if you have to bring it in later.

Another thing to check is to see if you're still under your extended emissions warranty, you might get it replaced for free

Hope this helps, and if you can, please post back and let us know what the solution is!