i put a hi-flow cat on my 01 LS and it threw a code 67 for invalid catalyst. which just means the secondary o2 sensor is reading more air then it should be due to the "higher flow." i was wondering if i moved the second o2 sensor bung(which is directly after the hi-flow cat) in front of the hi-flow, would it read correctly again and provent the code from beign thrown? i searched and didnt find the answers i was looking for.

 

Putting it front won't make it "better" because the 2nd O2 sensor is to detect the efficiency of the cat. The reading is supposed to be different than the 1st O2 sensor. If you put it in front, both sensors will read the same.

What cat do you have and was it new or used?

 

I'm a little confused myself on this one....code 67 is Catalyst System. Which is not the O2 sensor. The sensor is function properly. If it was not getting the correct reading, you would be throwign a code for that. (Code 41, 63, 65) Those all have to do with the 2nd O2 sensor.

Another thing that confuses me is...why is the O2 sensor mounted AFTER the Cat ? There should be an O2 bung so that the sensor actually screws into the cat. So why is yours not like that ?

And also, as it was asked, is the cat new ? used ? brand ? diameter ?

 

As long as it's after the catalyst material, whether inside the cat itself or inside the tubing before the flange, it will read the same. If you look inside the stock cat, the sensor is placed "in" the cat, but it's still AFTER the "bricks/honeycombs" (catalyst material).

 

The second O2 sensor is after the catalyst. Usually it's screwed into the converter housing, but it has to be downstream of the actual catalyst itself.

The O2 sensor codes mean the sensor is just not working. Code 67 means that the ECU 'thinks' that the O2 sensor is OK; but it doesn't like the reading so it's blaming that on a bad cat. The ECU can tell if the 2nd O2 sensor is unplugged or completely broken, but it can't tell whether it's making an accurate measurement.

 

i have a friend that did a b20 swap but had one to many o2 sensors, so because of this he jus ran one of the o2 sensors to where the stock airbox was so it would read clean air. it sounded like a good idea but dont o2 sensors heat up to like 600 degrees or sumthing like that. oh and also the hi-flow was brand new from the muffler shop that did the work for me. its ure basic hi-flow cat with 3in inlet and outlet. and the o2 sensor bung is directly after the cat on the piping. id say its no more the an inch away from the end of the cat. what i was tryin to get out of this topic was pretty much a solution to the ecu code. im tired of reseting the computer all the time and just flat out tired of seeing that dam check engine light illuminate my whole gauge cluster. please guys gimmie some idea what to do!!

 

Air box? You sure that wasn't for the IAT? O2 sensors are for the exhaust not the intake.

I'd suggest just getting an O2 simulator.

 

when i meant it was in the airbox i meant around that area so the air would be clean and hence the o2 sensor would read clean air. and i didnt do this it was my friend i was jus stating the fact.

 

Why would the o2 sensor heat up to 600 degrees? Maybe it would do that if it was still in the exaust but not if it was in the engine bay. Alot of people put the secondary o2 in the engine bay when they run gutted cats/test pipes.

 

thats what the guy that re-wired robs b20 and got it running told me about it. so i got that info from him and he seemed like he knows his ****

 

Perhaps he meant it doesn't fully function correctly until it heats up to 600 degrees? That wouldn't make sense either but if you run it to your engine bay you should be fine.