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Technicaldan, Technician
Category: Honda
Satisfied Customers: 110
Experience:  Accredited
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I left my lights on my car so battery went dead I have jump

Customer Question

I left my lights on my car so battery went dead I have jump started the car without key in the ignition but now the car won't recognize the key
JA: How old is the battery? Have you checked the battery gauge on the dash?
Customer: The battery is fine the green key keep flashing had this problem before but jumped it with key in the ignition honda said the key needed to be descrabled
JA: What is the model/year of your Honda?
Customer: Honda civic 56 plate but when I put key in the ignition the green key started flashing it has a start button all lights come on dashboard but it won't start
JA: What year is your Civic?
Customer: 2006
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: I hope to as I need to move the car as it is outside someone's house any ideas
JA: Anything else you think the mechanic should know?
Customer: When we took it to honda they said as long as you don't jump it with key in the ignition it won't spike the key so I left key in my friends house and proceeded to jump it so this wouldn't happen but it has so I am worried this will happen every time battery goes dead
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Customer: So what do you suggest
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Honda Mechanic about your situation and then connect you two.
Submitted: 1 year ago.
Category: Honda
Expert:  Technicaldan replied 1 year ago.


The flashing green key on the dash shows there is a fault with the immobiliser system, until that light behaves normally there is nothing much that can be done to start the vehicle.

A fault I have come across a few times on these after a flat battery is the key has been forgotten, it requires HDS (Honda diagnostics system) and a security access code from Honda's MARIS system to be done ordinarily, although quite a few mobile locksmiths these days can access the vehicles systems and code keys so it might be worth enquiring locally.

As for the key keep being forgotten, from memory it was the micu (multiplex integrated control unit - fuses and relays smart box) that was forgetting the coding, replacing it would be one way, (the next person to connect to the vehicle with a diagnostics machine, which someone will have to, record the fault codes so if it happens again there is history for diagnostics), again this would need coding and most likely with Honda's own system this time as opposed to a auto keys person, but do ask the local providers.

The last consideration would be to find out why the battery keeps going flat to avoid it, hopefully.