Engine Immobilizer and Key Battery

Got a 2017 Forester with remote keyless entry but NOT push button start.
If the battery in the key cap drains so low that the key push buttons
won't lock/unlock the door, can the engine still recognize the
immobilizer chip in the key and still start/run?
Reply to
Wade Garrett
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When the battery in my Audi's key got too low, the car started, but wouldn't keep running. Plus I couldn't use the remote to lock/unlock the doors.
Fortunately, it was a simple job to replace the button battery in the fob.
Obviously, an Audi is not a Subaru, and things may well be completely different, but I wouldn't take the Subie too far away from alternate transport until you get that battery replaced if I were you.
Reply to
Darryl Johnson
Mine isn't a fob. It's a metal key you insert into the ignition switch on the steering column and twist to start the car.
It looks like an ordinary key but with a big plastic head that has lock, unlock and emergency horn-blow buttons and a button battery inside.
I guess my question really is does the immobilizer system require the key battery to still have a charge...
Reply to
Wade Garrett
Well, chipped keys are common and many (most?) of them don't have a battery or buttons and they still manage to work because the car's ignition lock has a coil around it which signals to the chip circuitry in the key body. This is called a transponder IIRC. The big question is does your key use this basic method for this single purpose or does it combine all of the electronic functions into one. I know for certain that my 2018 OB with keyless start and remote buttons on the fob still has the transponder function built in and the manual says that to start the car when the fob's battery is dead you need to actually use the end of the fob to physically press the button (so that the car and fob transponder are oriented properly, I presume).
I guess one sure-fire way to find out would be to remove the battery and do the test, being careful not to lock yourself out somehow.
Reply to
John McGaw
Good idea, I think I'll do just that.
Yesterday I called the service departments at a few dealers and asked the same question.
Two said no battery required, one said he thought it was, two said they weren't sure. I appreciated the IDK answers- rather than just making something up!
Reply to
Wade Garrett
I was told not to cut off the big chunk of plastic or grind down the plastic on the valet key which I like to carry in my wallet. It also has the chip but there is no battery so I imagine if battery is dead in remote it will still start the car.
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