Check Engine Light Issues

Hello,
We have a Chevy Aveo (2007). We tried to go through emissions but it failed. We took it to Maxi Muffler and they fixed the catalytic converter and replaced the check engine light. We tried to go back through emissions again but the check engine light didn't come on when they turned the ignition switch so they stopped the process. We called back to Maxi Muffler and they indicated that the light came on when they checked it. They asked us to bring it back when we had a chance (they kept the car for 2.5 days originally and my bf works 3rd shift so won't be until this weekend). My boyfriend went to work last night and this morning when he turned the ignition, it illuminated! When he got home and turned the car off, he turned the ignition again and it didn't illuminate. Any idea what the heck is going on? It's running me insane. I apologize as I do not have the emissions codes that kicked out originally. Also, since they stopped the process the second time, we don't have any new codes. It's almost as if when the car is cold it comes on but when it warms it doesn't. Any idea what may be going on? I appreciate any help/suggestions. Have a great day.

Go to an autozone, pep boys, whatever and buy a code scanner. They are cheap now and there is no excuse in not having good information. If you have time order this: http://www.amazon.com/ieGeek®-Wirele.../dp/B00B3K2X4M

points on the name...

When you get the codes look them up and read about what is happening under the hood. Here is an article that explains a little more about catalytic converters.
The Misleading Nature of the PO42O Code - Eastern Manufacturing

Just clarifying, but it sounds like the issue that caused the emissions fail is the check engine light (CEL) did NOT illuminate when the key was first turned from OFF to ON (without starting the car).

I assume that's because the test facility checks to make sure the light hasn't been disabled to hide some other fault.

Quote:

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Originally Posted by thejedigoddess

We took it to Maxi Muffler and they fixed the catalytic converter and replaced the check engine light.

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So they actually replaced the CEL bulb? Sounds like this is their problem to fix.

Yeah I would take it back as something is not right, perhaps a faulty bulb, or dirty connection. The light should always come on with the key on to let you know it is working. If they changed the cat you may have had a P0420 code, once the ECM completes a monitor test on the cat it should clear the code on it's own.

Its good to see a Fellow Tennesseean on here! now just to clarify, is your aveo a Sedan or a hatchback? because if your aveo is a Sedan, it would be Virtually impossible for the mechanic to replace the Check Engine Light bulb, since 2007 was the year the Sedan got completely restyled and the Instrument Cluster was changed to where most of the Warning Lights are Surface Mounted LEDs.