Recently purchased a 2007 Cobalt for my new driver daughter. I purchased it for $300 from an elderly lady who could no longer drive. Even before we signed the pink slip, I was already visiting this site for answers about 2 weeks ago. The first issue was how to remove my key from the ignition upon discovering the battery was dead and the key would not come out. So no problem, I'll jump the battery to see if that works. But there was no battery under the hood. It was in the trunk. I can't open the trunk because the release button has no power and the ignition is holding my key hostage. Reading some of the posts here I learned that I could still jump the car from under the hood. Connect to the positive post under the red "+" cap and ground to the frame of the car. It worked! And I got the key released from the ignition. Replaced the battery and all was good. Started it up and discovered the exhaust system appeared to be missing!
Yep, the flex portion of the downpipe was half missing. The owner explained that it would not pass smog and she was told it needed a new Cat. In California, that's a "dealer only" fix, and they wanted nearly $1800.00. No Way.
Read about cutting out the flex portion and installing a new "fix" it portion sold on Ebay right before the first sensor leading to the Cat. But what if I spent the $60.00 for the part and found the Cat was bad anyway? SO, I pulled the whole assembly out of the car and patched up the hole in the flex portion with that muffler paste O'reilly's sells along with a few winds of muffler tape and a couple of 3.5" hose clamps. Reinstalled the down pipe/cat assembly with new gaskets and a bit of high temp copper sealer. Let everything dry for a couple of days. Disconnected the battery for 30 minutes to clear the CEL. Started it up and it sounded like a new car! Drove around for a few days making sure to follow instructions on how to pass all the drive checkpoints. Took it in to the Smog station and passed in less than 5 minutes. YES!
Other items fixed from reading posts on this site:
1. Bad power door locks.
2. Broken sunroof switch and bezel trim.
3. Leaking(wind only) sunroof seal.
4. Rough idle vibration(proper cleaning of throttle body)
5. Rear exhaust rattle (broken weld on heat shield)
6. Indicator light bulb in console for shifter.
7. New key programming
8. New keyless entry fob programming
And I am sure the list will go on! But it has been fun.
Thanks to the forum, Mods and posters. You made it all easy.