PRIUS C 2. Car Key Battery

car will start with a dead fob battery. check the manual, no need for a spare.

 

if you don't have smart key, why would it not start? isn't it like any other key fob? i don't have a c or manual, so maybe i'm off kilter.

 

perhaps the transponder has an emergency warning and low battery capabilty like the sks.

 

False. Prius C1 does not have an engine immobilizer.

 

Actually you can have duplicate key made for the C2 model at most major hardware stores, The key has to be programmed with vehicle's serial number. Cost is about $80. The blank number is TR47. Personally I carry a old fashioned non programmed key that will open the door only - when I lock myself out.

 

The battery in my fob lasted 3.5 years.

 

Relax.

Without the SKS, the battery is just for the remote door unlock. The immobiliser recognises your key when you insert it into the ignition.

I've been driving Toyotas (first a Camry, then a Corolla) with immobilisers since 1996 and although these were different in that they had remote unlock fobs that were not part of the key itself, I suspect it is highly unlikely that Toyota would design it in a way that went backwards from the old system. In that old system it was the (batteryless) key that the immobiliser recognised, not the remote unlock fob with its battery.

In any case, the battery will die gradually and you'll start to get annoyed that the operating range has reduced, notice the LED seems weak and end up replacing the battery long before it is totally dead.

EDIT: I just glanced at the manual and noticed the valet key does not have a fob. Leave the fobs in your house and try getting in and starting your car with the valet key. If it works, it will confirm what I'm suggesting here.

 

The immobilizer system uses a chip called a transponder in the keyfob or valet key. Power to operate the transponder is provided inductively from the car via a coil in the keyslot. If the battery in the keyfob dies, then the lock/unlock buttons will no longer work.

The easiest way to verify this is to remove the battery from a keyfob and test it.

 

What Rob H said... and what I said originally. There is no battery in the valet key and there was no battery in my Corolla key or my Camry key, which used the same immobiliser system and behaved the same way.

The battery in your key is for the remote unlock only. It is not there for the transponder function.

 

i'm throwing in the towel.

 

first off.. please stop using CAPS... it's rude and it would be considered as yelling.
but in this case... READ YOUR OWNER'S MANUAL.

the immobilizer chip DOES NOT require any power.. and also, you can start the car with a dead remote key... even with a Smart Key system (which you don't have anyway). the battery, i've seen last over 6 years, and even with it dead, the key will still start the car.

so.. no... you don't need an extra battery kept safe somewhere.. when the battery needs replacing.. sure.. just replace it.... the only thing the battery is used for in the key is for the remote lock/unlock... THAT'S IT... but hey!! so if you're battery dies and it doesn't work, you can insert the key into the damn door and unlock it manually.. like the old times when remotes weren't invented yet... or even new modern cars that don't come with remotes.

 

thank you phil.

 

A better form of emphasis is either the "quote" or the bold.