It is because the car does not recognise the key. It could be the decoder ring, key, wiring or recoder. It is usually the key thats failed. Give it a good knock on the steering wheel and try it. If it still dosnt work, try a few more times. If if it still dosnt work carefully take it apart and check for corrosion, if its corroded its probably beyond repair. Give the electronics a rub with your thumb, if it still dosnt work it could still be the key or it could be something else. It will need correctly diagnosing
The key is faulty or the immobilizer will not accept the code. remove the battery for 30 mins to allow the system to reset.
rear window defroster light keeps flashing
The overdrive off light flashing - indicates a malfunction has been detected
It is the electronic immobiliser. When the ignition is switched on, it should light up breifly and then go out once the transponder in the key is verified. If it keeps flashing then the key is wrong or uncoded (i.e it's been copied but then not programmed to match the car). In this case the car cannot be started.
if it keeps flashing on and off
From my experience this was followed about 2 months later by the whole display expiring. Renault replaced under part warranty for set price of £100 (March 2010). I found the trip meters kept resetting as well - don't leave it too late taking to Renault though, when the whole display started flashing on and off it added about 100 miles per flash to the odometer
I have Samsung tablet screen flashing and cannot turn off
overdrive light keeps flashing
might be a misfire in a cylinder...
Its broken.
Flashing lights - by Kanye West
If the hold light keeps flashing on a Kia Sportage a sensor may be malfunctioning in the light. The flashing light could also indicate that a speed sensor is going bad.