My "new to me" 95 SC 300 is displaying error code 27 (sub oxygen sensor. Only on Calif spec SC300's)

... but I don't see a sub ox sensor on the car.

Can anyone tell me how to identify a california spec SC300 and/or tell me exactly where to find the sub ox sensor on an SC300?

I know the ECU was replaced by previous owner, and he said "check engine" light has been on since it was replaced so I'm also wondering if the ECU is from a 400 or if there's some other issue that could explain the code.

Any advice is appreciated!

 

I have a cali spec car with a sub oxygen sensor. my ecu number is 89661-24332. I remembered it from looking for it 2 different times in 2 years. lol. but yeah I just had a recent code 27 and replaced my secondary o2 sensor, light went out pretty quick.
I don't know if you have a cali spec car, but if you put a cali spec ecu on a non cali spec car, then I can see that happening. idk if the 400 ecu fits the 300 or would even work. but its pretty simple to check the ecu.
just remove the lower panel on the bottom of the passenger side dash board, (the part that's under the glove box, should only be 2 push pins and the pull to rear of car. should come out.)
lift up carpet,
remove 2 10mm nuts from black ecu cover, viola! infinite access to ecu.

 

The 400 ecu in a 300 is NOT possible, the car wouldnt even start.

 

If you look under your hood there should be an emissions related sticker. If it's a non-california model (with original hood), it'll say something along the lines of "this vehicle is not for to be sold with a final destination of California" on it. The cali spec sc300 and non-cali (federal spec) sc300 have different emission standards as well as different ECUs. If he replaced the ecu and it came on after that he most likely used a cali spec ecu on a non cali spec car or he used an obd2 ecu from a 96-97 5 speed which could be looking for something but goes into a loop on a non obd2 throwing the code. (just to throw this out there if you're in california getting your car smogged make sure you tell them if you don't have a cali spec, tell them you have a FED SPEC and not CALI SPEC so they test on the correct specs)

 

Thanks!

I've checked and it's a Federal spec 95 SC300. I'll need to check the actual ECU to see if they used the wrong one, but assuming that's the case, is there any way to work around this so the ECU stops putting out an error code?