Hey, I have a tercel with about 323k on the chassis and i just did a swap with a rebuild...When i took off the exhaust portion I saw the o2 sensor was pretty white and ashy looking...if my o2 sensor needs to be replaced will it trigger my CEL?

Thanks,Matt

The engine light usually comes on when there is an emissions issue. If you have a bad O2 sensor it could very well turn on the check engine light. If your engine light is on heres a website to show you how to retrieve the codes and it has a list of the codes. http://www.troublecodes.net/Toyota/. I think all you will have to do is watch the number of flashes of the engine light to figure what code you have. It should flash and a number of times and then pause and then flash the code again, unless there is more than one code then it will flash one code pause and then flash the next code and so on then after the last code it starts over.