This may be a simple fix.
Have you cleared the code?
Some codes reside in the PCM memory until you clear them out. To clear the code, unhook the battery (make sure you know the code for your alarm if installed) and while the battery is disconnected press the brake pedal for about 10 secs. Leave the battery disconnected for a couple of minutes to be sure it gets cleared. Then reconnect the battery. Your car may idle a bit funny for a minute after reconnection while the PCM recalibrates all settings.
If you've done that and it's still a no go, then the PCM is located in the center console under the stereo and control panel. Make sure you are grounded when you handle it.
Only other advice I can give you is to get out of CA.
By the way, I've never heard of a $200 diagnostic fee, even from a dealer. Robbery.