Q: Car will not start - 2005 Cadillac CTS

Okay, so hopefully you have another vehicle to get around in. The first thing you need to do is get that code scanned. Once you have the code, you should be able to narrow down the possible problems quite a bit. It would not hurt for the time being to pull your spark plugs and inspect them. You can do an online search for "spark plug chart". Look for wetness or excessive blackening. Also, check the gaps on the plugs. If they look fouled, change them and make sure to gap them properly. You might be correct in guessing the ignition coil. To start, an engine needs fuel, spark, and compression; so verify you are getting spark, and get that code read and you should be well on your way to running again. If you would like to have this all taken care of for you, a certified professional from YourMechanic can come to your car’s location to diagnose the no start and have it repaired properly.