In attempting to help a fellow member with an immobilizer issue, a question came to mind but I cannot find the answer.

If the car recognizes the key, it has to be because of the chip and battery inside the key....which brings up my questions.

1. If the battery in the key dies (100%)....will the car still start if it can't recognize the key?

2. How are you supposed to know when the battery is near depletion? Or are you recommended to replace it every so often?

 

On the new Fit, there is a low battery warning on the dash for the keyless start/entry fob.

If the battery is too low to unlock the door, there is a key inside the fob. Then you can still start the car by touching the fob to the ignition start button.

 

What about my '09 Fit or wife's '14 CRV which are not keyless?

 

You could also do what I did. Put a spare battery in a tiny envelope in the console or glove box. If the fob is dead, use the key to open the door, then change the battery.

 

Hmmm...

Everyone else I think mis-read your post. Yes, there's a battery inside the keyless remote fob or Sport key for locking/unlocking the car. That's not the same as the matching chip inside the key that's part of the anti-theft/immobilizer system.

As I understand it, the key chip does not need a battery. It's a passive device that replies back to the car when interrogated, using the electromagnetic energy from that interrogation as its power source.

It's similar to RFID chips in credit/debit cards, or some driver's licenses in some states.

 

Yes, they were mis-reading.

So what you're saying that the car will NOT be immobilized if the battery in my key dies?

I'm certain that has to be the case as it wouldn't make sense to me to have a immobilized car when you have the key! I asked because the reading I did certainly made it confusing and left me wondering.

 

It's easy enough to test. Just take the battery out of the fob, then see if you can start the car and drive it.

 

The 2009-2010 Base-model Fits did not come with a keyless-remote key. That was standard only on the Fit Sport. There's no battery of any kind inside a Base key - just the immobilizer chip; if you wanted keyless-remote on the Base Fit, you needed to buy either a Sport key blank (that's what I did) or a dedicated remote fob and program it to work with your car.

Since there's no battery in the Base key, it stands to reason that the immobilizer chip works without one...

 

And that's where my question begins.

I have a 2009 Sport. Does the battery in the key have ANYTHING to do with the car recognizing the key? If the battery in the key is dead, will it make my key useless? Is the battery only for the key-less entry?

I am assuming the answer is no but some of my reading made it seem like it would.

 

All of the 2009 Fits have keyless-remote capability built into their wiring, but only the Sport models came with the transmitter (built into the key). It was an additional "accessory" for the base models.

To tell the truth, I have no absolute idea whether or not the Sport key battery is required to have the immobilizer chip work. However, it stands to reason that the key would still start the car if the battery was removed or dead.

I would be a very irate Fit owner if, when the battery actually dies, not only can't I open the doors remotely (a minor inconvenience, just use the key in the lock) but the car won't start!

 

As would I! Which is why I thought I'd better ask.

I would be mighty pissed if I couldn't start my car if I had the KEY but the battery was dead in it and now can't start my car!