Wow! You need a different mechanic, preferably a competent one.
"the sensor for the light was just messed up"?
I sure hope something got lost in translation. There are dozens of sensors, and there are over a thousand different causes that will result in the Check Engine light being turned on. There are varying degrees of severity that can be identified by how that light acts, but the most serious, by far, is when it's flashing. That means stop the engine as quickly as possible, not keep driving for a few more miles, and especially not keep driving it like that for a month.
The Engine Computer constantly monitors a lot of electrical circuits and operating conditions. When it detects a problem, it sets a diagnostic fault code. There are over 2000 potential fault codes that can be set. About half of them never turn the Check Engine light on. Those codes that relate to something that could adversely affect emissions must turn the light on. Whether the light turns off while you're driving, stays on but goes off only after you restart the engine, or is on all the time the engine is running, even if an intermittent problem went away, indicates how severe the detected problem is. The most severe is when it's flashing. That means whatever is wrong is causing too much raw fuel to go into the exhaust system and will overheat the catalytic converter. That will turn what might be a simple problem into a real expensive one very quickly.
The place to start is by having the fault code(s) read. They will indicate the circuit or system that needs further diagnosis or the unacceptable operating condition. (They never say to replace parts or that one is bad). THAT is what your mechanic should have done. If he thinks some mysterious sensor was "messed up", (hardly a technical term or diagnosis), why didn't he fix it?
Friday, September 5th, 2014 AT 7:06 PM