I have a 2013 Toyota Prius (regular size automatic, 36,000 miles) that I bought new from a dealership. For the last year or so it will not start once every week or two mainly when I'm leaving home. When this happens, it usually takes 10-15 minutes to get it started after trying all sorts of things and then not knowing if and what really helped. I tried the VIP Remote Engine Starter (not that I purchased this feature) to no avail. The remote engine starter is operated by pushing the “lock” button on the key-less entry fob in a quick, three-step sequence. This problem with starting my car seemed to begin when I stopped taking it to the Toyota dealership. I now take it to a local car shop that I trust. However the shop explained that only Toyota could fix this problem that they thought had to do with theft protection, which is nothing I ever asked Toyota to turn on and this was never a problem for the first nine years I had the car. I haven’t taken it to the dealership because I don’t trust them. They always tried to over charge me at the check out counter and car manufacturers are starting to install surveillance measures like kill switches https://www.yahoo.com/autos/law-install-kill-switches-cars-170000930.html
it will not start once every week
does it crank?
no, it remains silent during the times when it will not start.
I gather the mechanic tried the simple stuff first, like changing the key fob battery?
Will the car even turn on?
I changed the key fob battery recently and that did not help.
The car usually takes 10-15 minutes to get it started after trying all sorts of things. It does not turn on in that 10-15 minute period.
had to do with theft protection, which is nothing I ever asked Toyota to turn on
passive immobilization is something built in to all vehicles (unless you drive a Kia which has been prominent in the news for thefts).
Get your battery + alternator load tested. Check all fuses and relays.
Just to make sure, you tried it just with the normal starter button in the car, right?
When you tried it, what happened exactly? It sounds like it does not even start the electric motor, the hum you initially hear when hitting the starter button, just before the motor starts?
Do you have both key fobs?
