Check Engine Light??
 

Hey so I was driving down the west side of Snoqualmie pass on Friday night heading home from some wheelin over at Moses Lake when all of a sudden my Check engine light comes on...I was already down to the nearly flat part like 10 mi east of issaquah so there wasn't much stress on the motor just pulling smoothly. I checked the oil and coolant and both were fine (no overheating) I called my dad up to ask if I should just keep drivin home especially with all the money we just put into the motor and he said bring it home, it's a yota it'll be fine. So I restart it and drive home everything seems fine all the powers still there and no funny noises but I haven't gotten to check my fuel economy yet, on the 2 earlier tanks that were spent on the highway going there I got 23 then 22 mpg and so far it looks like I'll be getting around 20 with this tank. Any ideas? Could it be a G52 or whatever the knock sensor code is?
Thanks

I wouldn't worry yet over any slight change in mpg. Did you do the motor work yourself? You need to short the E1 and T pins in the diagnostic box behind your battery and go from there. No reason to jump to conclusions without reading the codes.

Yes I did the work myself, and I checked the codes today and its a code 21, O2 sensor code. Is there a way to check and see if the O2 sensor is just dirty or should I just replace it? Also I've heard that people with headers have gotten this code too, can anyone chime in of on this?
THanks

There is a procedure for checking the O2 sensor in the Toyota manual. If you don't have one check this link.

http://www.personal.utulsa.edu/~nathan-buchanan/93fsm/

specifically, O2 sensor section...
http://personal.utulsa.edu/~nathan-b...01heatedox.pdf

My opinion is not to replace it unless it tests bad or you just feel like spending $50. I have downey headers and have never gotten the 02 sensor code. It's not uncommon for something else to go wrong in the engine and cause the O2 sensor code. I would pull the EFI fuse to reset the engine computer and see if the code shows up in a few days. Also, use a multimeter and check the sensor.

Cool thanks...I'll give that a try when I get home today