My 2010 Prius suddenly started beeping every 20 seconds and the security light keeps flashing whether it is locked or not. This light has NEVER come on in the 10 yrs I have driven this car. AND it happened just after the expensive spark plug replacement last week. Any connection?
Are you getting a message like "key detected in car"? In any event, the security indicator light should flash after the power switch has been turned off. If it hasn't been doing that, you may have a non-functioning security system.
