Engine Light turns on and off Options

[dnyluong]

I just recently got my celica back from the mechanics after a tune up and the installation of my KYB's and Teins.
I took her for a drive around the block and the engine light came on and i was in a state of WTF, so i called up my mech, told him what was up, and he told me to disconnect a fuse and keep it out for a minute to reset the light. I did that, and the light still persisted, I drove around some more an about 20~ minutes of driving the light turned off.

Now every once in awhile the light will turn on, stay on for about 20~ minutes then turn off, Mech said it shouldn't be anything serious, but I'm start to panic a bit everytime it turns on. Also while acccelerating I hear a slight knocking sound, usually in 2nd and 3rd gear. Any Ideas on what that is? Also my right rear wheel squeaks whenever I break.

All these thing's are just adding up and I don't know what I should do about it since my mechanic is out of town for another week and I'm relatively broke right now because I just got back from a week of camping.

Any suggestions or advice would be greatly appreciated. Thanks guys.