Alright, I have a 92 SC300 and my check engine light has been on. I did the self test and came out with code 27 and code 71. I already fixed code 71 because I had some serious carb build up in my EGR. Now code 27 I thought was the sub O2 sensor but I am not sure which one is the sub sensor. I am only finding 2 O2 sensors on the car right on the Headers so which one is the main sensor and which is the sub sensor. Any help would be greatly appreciated, thank you.

 

Ok, not being rude but I guess no one can help me out. I have been on several other forums as well and no one responds. I guess I will just have to figure it out the good old fashion trial-and-error way. If you do know somethin, please let me know, thanks.

 

For what it's worth (and I know you posted this over a year ago) I am having the same problem........ ????????

 

I think I have narrowed down the problem....

I changed ecu's and didn't get the light. I too only have 2 O2 sensors and don't have the 'secondary sensor' like some cars. I do have a plug inside the car for one but there was never one hooked up from the factory. I too got code 27 (secondary O2) and changing the O2 sensors didn't help. I changed ECU's and it seems to be okay now. I want to give thanks to slappy96 for hooking me up with a computer.

Thanks,