Auto Parts: Chevy Impala 2004 (3.8L) Mass Air Flow sensor, mass air flow sensor, mass air flow

Question
Hi Mike,
Recently I had the check engine light come on while I was driving my Chevy Impala 2004 LS (3.8L) so I took it to a mechanic to check it.
Now this is what the mechanic said:
The MAF sensor in the car was missing!! When I asked how this could've happened, he said that it could've been stolen over night and that the check engine light came on after I drove it 45 Km from the time the sensor was missing. A new one would cost me about 600$
The sensor is located on the engine under a hood and to steal it, someone would have to figure out how to open the hood and what to look for in the middle of the night.
I'm not sure if this mechanic's story is plausible. Do you think I got ripped off? or is it actually possible for something like this to happen?
Thank you

Answer
    Well, it certainly would be easy to steal.  And, if your door was unlocked, then accessing the underhood area would be very simple.  I haven't heard of these things being hot items on the theft list, but if someone needed one and didn't have the hundreds of dollars needed to replace it, stealing one would certainly look like a viable option to the morality-impaired.  I can understand your mistrust of the mechanic for the same reason, but I can't imagine choosing that particular item on which to rip you off.  Now, if the mechanic owns a late-model GM FWD car, I might be a little suspicious.  But good mechanics with busy shops can pressure their suppliers for parts for their own cars, and the suppliers are happy to do it to keep their business; I've been through that process dozens of times.  However, you could buy a new sensor for less than $200 and put it in yourself (very easy to do).  Unless the thief stole more than just the sensor itself, then there's no telling.  I think I'd discuss this price with the mechanic, he's charging you too much.  Tell him you want an A-! Cardone rebuilt MAF and nothing other than what's necessary to complete the job.  The computer will reprogram itself once the new sensor is in and the car's been driven for a little while.