My OBD2 is throwing me a SES for the past year. So, I went to autozone to get the code and it came back as a "catalyst inefficiency" on bank one.
Anyone know what causes this? My cats are Random Tech. I called them last summer and they said it was probably my o2's. They're all new though, and if it were my 02's wouldn't that throw an o2 sensor code instead of a catalyst inefficiency? Is it possible the cat plugged up already? The car seems to run fine. It pulls steady through the RPMs although I do seem to be down about 40hp for my mods (i only dynoed 297rwhp and 307rwtq on the dynojet). Maybe this light is the roots of my lack of power.

Any one have any insight to this?

 

The code is set when the PCM does not see the readings it expects from the after-cat O2 sensor. Could be a problem with a dieing cat, or a faulty after-cat O2 sensor. A quick way to check... swap the after-cat O2 sensors from side to side. If the problem stays on Bank 1 (drivers side) it means the cat is failing. If the problem follows the sensor to the passenger side, its a faulty sensor. The only other possibility would be a wiring harness problem on the drivers side.

 

i can't swap them with this RT y-pipe. one reaches and the other doesn't if i do that. is bank 2 the passenger side or drivers side?

 

No he is saying take out the sensors and put them on the other side. Bank 1 is the drivers side and bank 2 is the passenger side I think.

 

I understand what he's saying. But my driver's side cats sit back much further than the stock ones did and when I try to put the driver's side 02 sensor on the passenger side, the wire is not long enough, it needs an extension.

 

So right now you don't have an O2 sensor after your cat on your passenger side? Are the pigtails different legnths or something that would keep one from fitting in on the other side?

 

I have Random cats but decided it was cheaper and better to put 02 sims in than get another rear 02 sensor.
I only have to pass an OBDII scan for emissions and both 02 and 02 heater monitors read ready with the sims after a few tanks of gas.

 

yeah. right now their is an 02 sensor on each side, but the pigtails are different. One is a GM sensor, and the other is a Bosch which has a longer set of wires. I may try to extend the wires myself tomorrow and then swap them.

 

my car did the same thing, except, i have stock cats. Ive had the bank 1 sensor 1 code before, but then it came up bank 1. The real test to see if its the cat is if ur car bogs and has a miss throughout the rpm band. If it doesnt then its most likely the o2, but if it does have a constant miss then its ur cat.

 

Do NOT try to extend them yourself! I did that for my O2's and they work fine for about a month or so but then they will go to crap. If you really need extensions in the first place, might as well order some and go from there.

 

I extended the first pre-cat driver's side sensor and it has been working fine for a year now. How much are extensions these days? Or simulators?

BTW, I don't have any missing or bogging at all. I'm just missing power throughout the entire RPM band and I can't imagine a bad 02 sensor would effect me THAT much. Perhaps my valve lash is too tight.

 

Which side is the Bosch on?


Am I missing something here or did you answer your own question

Read the above quotes again if you don't see it. It's been working fine for year and throwing a code for a year.

Remember that the PCM compares the front O2s to the reading at the back O2s and expects a certain time to go by before seeing the resultant change at the rears.

 

i extended the front bank 1 o2. And the rear bank 1 o2 is the GM one without the extended harness.
Bank 2 had a new Bosch in each position. Bank 2 is the cat throwing the code.
I can't wait to get switched over to OBD1 so my rear o2's go away.

 

Having trouble following you but all I can say is usually Bosch don't work in OBDII. Never could get them to work in my 99 P-up.

Why don't you just swap the O2s from the side the works and reset the code and try it again.

 

my bad, i see the confusiion now because I originally stated "bankone" was where the problem was, and they I started saying it was on "bank two." The code stated that there was a catalyst inefficiency on "bank two."

I reset the computer a couple days ago, I drove 60 miles back into Columbus and the SES light never came back on. I unhooked the battery again lastnight to install my LT4 KM and drove another 30 miles to see if the car "felt" any better and the SeS light still never came one. Maybe this car is just playinig head games with me...much like my ex-girlfriend, I think driving it off a cliff would fix the problem