My Honda cranks but won't start and the green key light is flashing. What's wrong?

If your Honda cranks but will not start, and a small green key is flashing on the dash, the car did not recognize the chip inside your key. Honda's own manuals call this the immobilizer indicator. If it blinks, the system does not recognize the coding of the key. A Honda service bulletin describes what you are seeing: "the engine cranks, but it does not start." The buttons and the chip are two separate things. On many Hondas you can program the buttons yourself from the driver's seat. The chip has to be programmed with a tool. The most common reasons we see are below.

Why do the buttons work but the car won't start?

A Honda remote head key does two jobs. The remote sends a radio signal to lock and unlock the doors. The transponder chip answers the car when you turn the key, and the car will not start until it hears the right answer. Programming the remote does nothing for the chip.

How does this happen?

We see three ways.

The battery change. The chip is a small piece that sits loose inside the key head. When the key is opened to change the remote battery, the chip can fall out and nobody notices. The remote keeps working on the new battery. The next time the key goes in the ignition, the car cranks, the green key flashes, and it will not start.

The replacement key. A new key ordered online, or one that came with a replacement ignition, arrives cut but not programmed. On many Hondas the owner can run the remote procedure and hear the locks cycle. That programs the buttons only. The chip has not been introduced to the car, and the car will not start.

The decorative ring. This one is not the key. Honda reads the chip through a receiver inside the trim around the ignition switch. A decorative ring stuck over that trim can block the signal. The ring has a metal backing, and metal blocks the signal. These are sometimes sold as bling rings, rhinestone rings, crystal rings, or ignition stickers. One owner's video shows a 2007 Accord that cranked with the green key flashing until the ring was peeled off the ignition. Then it started.

Which Hondas let you program the remote yourself?

Mostly the older ones, with a key you turn. These are the same years whose ignitions wear out (see our Honda ignition repair page).

Accord 1998–2012 · Civic 1996–2006 · CR-V 1997–2006 · Pilot 2003–2011 · Odyssey 1997–2010 · Element 2003–2011 · Ridgeline 2006–2014 · Fit 2007–2008 · Acura MDX 2001–2013 · Acura RDX 2007–2012 · Acura TL 1999–2008 · Acura TSX 2004–2008

Newer Hondas and Acuras, and the hybrids, do not let you program the remote or the chip yourself. On those, nothing programs without a tool.

Can I program the chip myself?

No. The chip is programmed with a key programmer connected to the car. On these Hondas it takes about 15 minutes once a locksmith is at the car.

What should I do?

If there is a decorative ring stuck around the ignition, peel it off and try the key again.

If you changed the battery recently, look inside the key head. If the chip is gone, we put a new chip in your key, or a new chip and a new key shell if the key is coming apart.

If you have a new key that locks and unlocks but will not start the car, it needs the chip programmed. Have the key with you. It does not need to be a Honda key.