My car is misfiring piston #2. How much should this cost to repair?

You need to have fuel, spark and compression for the cylinder to fire. Most shops, like ours, charge a diagnostic fee of about an hour or in our case $108.00 to have the technicians inspect the vehicle. You can remove the coil, spark plug and inspect it yourself. When was the last time you tuned the vehicle up? How many miles are on the current set of plugs.

I have a 2007 Cobalt. I had the same problem with mine, piston had to be replaced along with a bunch of other stuff that shouldn't be necessary on a 5 y/o car. The mechanic said this happened because GM didn't design the engine in a manner that would allow the carbon to release, therefore it builds up and you have issues. The repair cost $1800.00. This vehicle has solidified my decision to never purchase another GM product again...I don't care if it's just a dang keychain!!