After two days of rain, car started in the morning and ran fine for a short trip. Later in the day it wouldn't start. It cranked briskly but wouldn't catch. Gas tank full. After ignition switch is turned on for a few seconds, the colored lights on the rear view mirror start flashing. Remote seems to work, locks/unlocks fine. I disconnected the negative terminal of the battery and reconnected, then reset the alarm. No change. Googling around indicates it may be the crankshaft position sensor, but would this sensor go bad abruptly with no warning? Car has 85k miles, but considerable rust. Maintenance is up to date. Any advice would be appreciated.