Toyota Repair: Malfunction indicator light (MIL), fuel air mixture, malfunction indicator light

Question
The orange MIL on my instrument panel stays on, but the car passes our Emission Control check every year with good grades. I took the car to my Toyota dealer and he worked on it.  When I got it back the light was off, but came on again after two days. The mechanic just scratched his head and didn't know how to fix it. I am handicapped and can't get at the bulb from behind the panel, or I would just remove the bulb. I have been told that this light can be turned off manually under the hood.  Can you tell me how to do that?  Or, is there a fuse or circuit breaker for the light?  If so, where is it?
Thanks,
Bruce

Answer
Hi Bruce,

I assume you mean the check engine light. All they did was clear
the codes in the ECM/PCM and of course it will come back on. I need
more info! What model and year Toyota? is the light on permanently or comes and goes? Is it on all the time or not on when you first start the car or after your driving for a few minutes? I could find the issue if I was at the car but we don't have that option so I need more info to pinpoint the problem. Does the car idle smooth, accelerate fine without stumbling? I would not recommend disconnecting the bulb, or putting electrical tape over the light.
Its there for a reason. and if this issue is cured some other problem
might set it off. Two common things with Toyotas set that light on;
one is the gas cap can be loose, missing, or bad, the other is the fuel/air mixture can be slightly off and the oxygen sensor(02) reads that in the exhaust gases. That doesn't mean the 02 sensor is bad! I've seen way to many of them replaced when that is not the problem, it there to detect,too many mechanics don't understand sensors and replace them. Has the car had a tune up? Worn plugs, dirty air filter, vacuum leak,loose or crack in intake hose can affect the sensors.

Tim,
ToyDoc