Catalytic Converter or Bank2 o2 sensor short?

[97NABISCO]

Hi All,

So I previously posted with issues trying to pass smog here in CA.

I have a stock 97 5spd 240. The initial issue for the CEL I was throwing was because I had an auto ECU in a manual 240 (original ECU fried due to bad seal in windshield).

So after a long search, I found an OBDII, 97, manual ECU!!

Installed that, still threw a CEL...

I have since then changed the Bank1 and Bank2 o2 sensors (Bank2 I have changed twice) and the car still throws CEL.

The smog spot told me it's throwing because of Bank2 o2 (that's why I changed it twice).

So, my question is, do you think it's the cat (the one right in front of the Bank2 o2 sensor) or that the issue could be a short in the communication from the Bank2 o2 sensor to the ECU? I have never changed the cat in this car and I have had it for about 4 years now and I know the previous owner never changed it... car has about 215K miles on the clock.

Thanks for the help ahead of time... at this point my car is 6 months expired in registration... :(

[brndck]

step one: go get an obd2 scan tool and check the codes yourself

[97NABISCO]

step one: go get an obd2 scan tool and check the codes yourself

Hey!

He scanned it with a scan tool and told me the Bank2 o2 sensor was the issue (not responding/reading/sending info).

I'm wondering if that's the case is it the CAT or the sensor... I can't imagine replacing it twice and having the dumb luck of getting two bad ones.

[brndck]

Hey!

He scanned it with a scan tool and told me the Bank2 o2 sensor was the issue (not responding/reading/sending info).

I'm wondering if that's the case is it the CAT or the sensor... I can't imagine replacing it twice and having the dumb luck of getting two bad ones.

odds are, your cat is worn out. if you can, borrow one from someone with an obd2 s14, install it, clear codes, and drive it long enough to set all the monitors, then smog your car.

at that point you can either swap yours back in, or order a new one.

[97NABISCO]

odds are, your cat is worn out. if you can, borrow one from someone with an obd2 s14, install it, clear codes, and drive it long enough to set all the monitors, then smog your car.

at that point you can either swap yours back in, or order a new one.

Thanks!

I have been looking up where to get a new cat for the car and it seems as though there are a couple options. I have heard of people buying cheap cats and them only lasting a couple years (which basically makes them have to buy one every two years for smog).

Can I just buy one of those and only install it when I need to smog the car (granted I'll have to clear codes again and go through the whole drive cycle bit)?

Do you have any recommendations for brand?

Thanks man!

[jedi03]

catco and random technology make some good ones...I have run 2 random tech cats for years with no issues!

[Juantwo3]

Before you waste time

1. A catylitic converter will 99% of the time throw a "below efficency threshhold code"

2. If you have replaced the ecu and 2 o2 sensors and you still have the same problem get a scan tool that read live data amd monitor the wave forms of the o2 sensor that you think is bad, if you cant do that back probe the o2 and compare the resistance to what the fsm says it should be.

I strongly think you have a wiring problem just based off your description symptoms