Not-coded key suddenly works on the car

Hummm, this is very interesting. Where did you get the brand new not coded key from? Dealer, locksmith, or online seller? Was it really brand new, or refurbished "virginized" fob? I don't have an explanation for what happened to your key, but I have purchased a refurbished "virginized" fob online for my PRIME, but have not done anything with it. I may try taking it with my working key to see what happens.

My understanding is that for the new fob to work, the key has to be programmed to ECU by using special TechStream program that is only available to authorized Toyota dealers or trusted registered locksmith.

 

(*) Is the original key far enough away from the car to be certain that the car isn't starting from it?

(*) Is there any chance at all that the lost key is actually inside the car? In another recent thread, the car has responded part time, but not all the time, to the missing fob lost somewhere inside.

I won't completely dismiss the possibility of the car self-registering a virgin fob while a known registered fob is present. While this seems quite unlikely, and not anything I've ever heard of on previous generations, I won't stick my neck out to declare that such a new feature for Gen4 is impossible.

 

Take the non-coded key out and away from the car, then try again, verifying that the car doesn't start.

If it still starts, then my bet is that the 'lost' key is somewhere inside the car, and very recently shifted into a detectable location or condition.

If it doesn't start, then keep pursuing the apparent self-registration of the virgin key.

 

^^^ This is where my money is at too. The lost fob probably slipped down and out of previous owner's pocket and is sliding around under the seat. It's battery maybe low to boot.

 

At least testing for this is quick and easy. Not a certainty that this is it, but the probability is high enough compared to the minuscule time and cost of the test, that it is very well worth testing for.

A low battery should trigger an alert on the dash display. It is tested for and coded into the digital transmission by the fob itself, not judged by signal strength received by the car. My spouse's key has that issue right now.

 

Have you asked the dealer who sent you the key?

Put it down to a 1 in a million fluke.

 

So, are you saying your local Toyota dealership coded the key before mailing it to you? Is the physical key cut?

 

Though failed, I saw this as a necessary check before more costly paths were explored.

Problem is, I don't believe that a fob can be fully coded remotely before mailing. The fob also must be registered by the car, which requires a data connection to the car.

The only thought coming to mind is that possibly Toyota might have added a new software feature to this latest generation. That is, when the car detects a new virgin or pre-primed fob, in the presence of an existing properly paired fob, it is recognized as a new fob intended to be paired, and automatically completes the process. But I haven't seen any discussion of such a feature here, so this 'incident' is worth exploring.

Done well, this sort of feature would avoid a good chunk of the hassle and expense of adding a new or replacement fob. Done poorly, it is another security hole.

 

Yeah, but it could also mean that its easier to clone a key fob and steal the car now. Hopefully this isn't the case, and if it is, they've built in safety measures.

 

Agreed. It is indeed very strange that unregistered virgin fob is working without an effort. Is there anything different for Gen4 sold in EU?

Yeah, if it's true that having a virgin fob with a registered working fob is all required to make it work on that car, it can be a huge security issue. I can see a scenario in which someone could have a virgin key fob and just ride along on any Gen4 to make it a working key for that vehicle. There has to be some other explanation for what is happening here.

 

Maybe the dealer just found the other missing key, which could have been in brand new condition if it wasn't used, and posted it to the OP ?
The only mystery then, is why it didn't work the first time.

 

There has to be an explanation