I visited the dealers and they want $600.

Quote was probably new transmitter plus programming.

Will the 2017-2024 FOB work?

No.

Transmitter 88835XC00A

https://parts.subaru.com/p/Subaru_2025_Forester-25L-HYBRID-Touring/Transmitter-Keyless-Access-SMT-Transmitter-NA/120592600/88835XC00A.html

Key Blank 57497VC000

https://parts.subaru.com/p/Subaru_2025_Forester-25L-HYBRID-Touring/KEY-PLATE-BLANK-MASTER----Blank-Key/142361721/57497VC000.html

Locksmith should be able to program. Aftermarket keys I have found are hit or miss.

 

I checked Amazon and the part number for a 2017 to 2024 Forester key fob is PN 88835. Same as what is posted for a 2025 in reply. ?????

 

You're missing the rest of the part number, you have to look at the ENTIRE number. Probably aftermarket if you're looking on Amazon anyways. Yes the transmitters look identical, so I understand why it's doesn't make sense that it wouldn't work.

Transmitter for 2019 (not 2017) to 2024 Forester (and some other models) is 88835FL032. This is not compatible with a 2025 model year SL Forester, sorry.

https://parts.subaru.com/p/Subaru_2024_Forester-25L-Limited-wEyeSight/Transmitter-Keyless-Access-SMT-Transmitter-NA/95999922/88835FL032.html

 

@j3rf Just to add to the confusion..... Agree that the 88835FL032 will NOT work for the OP's 2025. But it doesn't seem to be a universal fit for SK Foresters either. I need one too, but the lookup indicates that the FL032 is universal for the later (2021-2024 models), iffy on the earlier years. The match for my 2019 Forester (and even down to some other Subaru vehicles to 2017) is the 88835FL03C. Extra nice if true, because it happens to be cheap!

 

@Fibber2

Bit of a weird year split in my opinion, probably something to do with the supersession of the part number since both 88835FL030 and 88835FL031 both list the 2019 model year Forester.

 

If I needed a third fob for my 2025, which seems to use 88835XC00A, I would not be able to use a fob from a 2018 XT, which seems to be 88835CA311?

If the 88835CA311 can't be used for my 2025, could it be used as an additional fob for any of the vehicles listed under fitment for the 88835CA311, if the fob had previously been used for a 2018 XT?

 

@Botnik

That is how I am understanding the part number compatibility, yes. 88835CA311 should work for any of the models listed.

 

88835CA311 should work for any of the models listed.

Is it true that if the fob has been used with one vehicle, it is somehow written to, and can't be used with a different vehicle after that?

 

OP might want to call a mobile locksmith.

I got a quote for $265 from a service specializing in car fobs here in Atlanta.

They come to the house in a van full of fobs. No part number search or shipping required.

 

I looked at the back of my key fob and it says model 14AKB

I called my dealer parts and he said if I add a key fob, the other two original keys must br reprogramed at the same time. Otherwise, only the new key will work and the two original keys won’t. Price for the new fob with door key is $260.43 and to program

Got cut off post. To continue, $260.43 for new fob and key and $280 to program new key fob, cut new door key and reprogram the 2 original fobs for a total of $540.43 plus tax. So $600 here in CA.

 

I called my dealer parts and he said if I add a key fob, the other two original keys must br reprogramed at the same time. Otherwise, only the new key will work and the two original keys won’t.

You only need one key at the time of programming if you don't delete the other keys before programming the new key. You are not required to delete all the other keys while programming just one transmitter. Parts guy is incorrect.

 

@Botnik

As far as I know, nothing is written or changed on the transmitter side when registering a key. I bought a used OEM key off eBay as a third spare for my 17FXT, programmed normally and works perfectly.

I am curious if you can program one transmitter to multiple vehicles.

 

I am curious if you can program one transmitter to multiple vehicles.

Yes you can program one remote to two different vehicles (It will be accepted and registered), but due to the rolling codes, the keyfob will be not in sync to the other vehicle anymore.

So therefore it will only work on the last vehicle registered.

You may be able to get it to work that way if both foresters were registered at the exact same time with a single button press of the remote, but then the cars would have to forever be kept together for the novelty to continue, if you unlocked one car without the other one present, the other car will be forgotten. (just a guess)

 

due to the rolling codes, the keyfob will be not in sync to the other vehicle anymore.

So therefore it will only work on the last vehicle registered

With some garage door openers, they allow for some look ahead, in case the buttons on the remote are pressed when away from the garage door. So on some, you can press the button say, 255 times and you can still go home and open the garage door. But press it that 256th time when away from the garage door and you'll be out of luck. I can envision a Subaru fob being pressed when away from the car, like when a kid is playing with it, or you are trying to lock/unlock when just out of range and you have to press a few times before the signal is received by the car. I wonder what the fob and the car tell each other when they are in contact with each other, without the user pressing any fob buttons. Like, when you're in the car and your fob battery is almost dead, and once in a while, the car tells you that the fob is not detected. I wonder if it's just "hi, I'm here" or if there is any synchronisation or anything else happening. I guess another thing that could happen is you get into the car with the mechanical key or by pressing the buttons on the hatch, or the sensor on the door, and then you start the car. Maybe that's RFID and a different system from the button press, and maybe that doesn't advance the button codes.

I bought a used OEM key off eBay as a third spare for my 17FXT, programmed normally and works perfectly.

Okay, good. I read somewhere that the fob somehow gets "paired" to the car and it's permanent and after pairing you can't use the fob with another car. Good to know it's not true.

 

You may be able to get it to work that way if both foresters were registered at the exact same time with a single button press of the remote

@OuchDamn

Well in order to register the transmitter to the immobilizer on keyless access vehicles, you hold the transmitter to the push start button. So you wouldn't be able to register them at the same time. Wonder if one of our used car SJ Foresters has keyless access.

 

Remember that the fob has multiple transmission modes that all have to be paired.

1) The nearfield transmitter that unlocks the doors when you reach for the handle and press the push-to-start button.
2) The lock / unlock buttons that talk to the RKE via 315 (old) or 433 (new) MHz transmitters.
3) The passive encryption chip (the "wedge") that responds to the immobilizer as your backup should the battery powered nearfield system fail.

You are setting up all 3 systems at once during the programming.

A few other things concern me, and an extensive search brings up conflicting answers....

A) Do you need to bring all keys? On my last two local locksmith key adding adventures (2014 Outback and 2018 Forester - both with conventional keys - so only passive G chip for the immobilizer and buttons for the RKE) I was instructed to bring all keys. Everything was deleted, and once in programming mode all keys were inserted and the engine started. At the end (original 2 keys with buttons and one valet, plus the new button key for our daughter), 4 keys were newly programmed to the vehicle, and then the vehicle was taken out of program mode. But it was done with an Autel IM608 tool, and not SSM4. So @j3rf is likely correct. With the right programming knowledge, deleting all keys might not be necessary. Just one original gets wiped and reset, and one new key gets programmed.

B) Ebay and other sellers often claim that their used fobs have been "wiped" / reset, allowing them to be paired with your vehicle. True or false? Apparently not all vehicle systems are identical. Used Toyota smart fobs can be reset using a Tango box that captures data from your master key and overwrites that onto your used Ebay key to remove it's old vehicle association. So apparently the key/vehicle pairing can be bidirectional. I'm still reading to see if/how this works with Subaru smart fobs.

Looking for verification and a Subaru-specific test case, but.......

Googling: Can a Tango box reset a used Subaru smart key fob?

Gave this:
Yes, a Tango key programmer, with the appropriate specialized software activation, can reset a used Subaru smart key fob so it can be reprogrammed to another vehicle.
Subaru dealerships typically cannot or will not reset a used smart key fob, as their diagnostic tools are designed to program new fobs to a specific vehicle's system, not to "virginize" used ones. However, professional locksmiths or technicians using advanced aftermarket tools like the Tango programmer can perform this reset.
The specific software activation required is often labeled as "Tango Software Reset of Toyota/Lexus/Subaru Smart Keys" (covering 40, 80, and 128-bit keys). This function allows for the unlocking/resetting of the key's transponder chip wirelessly, effectively wiping its previous vehicle data and allowing it to be treated as a new, "virgin" key for the programming procedure in another compatible Subaru.

And this is a statement from the North Coast Keyless site for a Subi Forester used smart remote:

• All Lightly Used Remotes Have Been Professionally Cleared and are Ready to Program to Your Vehicle Upon Arrival

 

You are setting up all 3 systems at once during the programming.

This is correct. Key start versions need the immobilizer chip and unlock remote programmed to the BIU separately.

Do you need to bring all keys? On my last two local locksmith key adding adventures (2014 Outback and 2018 Forester - both with conventional keys - so only passive G chip for the immobilizer and buttons for the RKE) I was instructed to bring all keys. Everything was deleted, and once in programming mode all keys were inserted and the engine started. At the end (original 2 keys with buttons and one valet, plus the new button key for our daughter), 4 keys were newly programmed to the vehicle, and then the vehicle was taken out of program mode. But it was done with an Autel IM608 tool, and not SSM4. So @j3rf is likely correct. With the right programming knowledge, deleting all keys might not be necessary. Just one original gets wiped and reset, and one new key gets programmed.

I'm only stating how my experience with immobilizer registration works within SSM, I don't know how aftermarket tools work. If they wipe all keys when a new one is registered automatically, that seems annoying. There is an option to delete all registered keys in the immobilizer, and that is something I do when customer is requesting a new transmitter due to a lost key. Don't want someone with a lost or stolen transmitter to be able to use it to access or steal your vehicle.

Subaru dealerships typically cannot or will not reset a used smart key fob, as their diagnostic tools are designed to program new fobs to a specific vehicle's system, not to "virginize" used ones. However, professional locksmiths or technicians using advanced aftermarket tools like the Tango programmer can perform this reset.

In a professional case, sure a dealer might not want to program a used or aftermarket transmitter due to issues. Like I stated though, I purchased a third transmitter off of eBay for my personal car and was able to register it perfectly fine through SSM with my vehicle's immobilizer. To my knowledge, there isn't a reset process for the keyless access remote transmitters. So perhaps it is an aftermarket scan tool issue where the transmitter needs "reset" before programming.

 

Thanks for responding @j3rf . There is certainly a lot of 'mystery' surrounding the process of key registration, and a lot of it likely stems from the use of generic aftermarket tools (local locksmiths) vs dealerships (SSM4 in the case of Subaru).

I've used Toyota's Techstream software on a laptop to add a smart key fob to our 2015 Sienna. I bought a used (but reportedly 'wiped') 6 button Toyota OE fob from North Coast Keyless. I did NOT have to delete all keys, IIRC. Just used one original and the purchased used fob in the process to up the family count. It's possible that Techstream had the option to just add one or delete all and add all, but it was years ago and I just don't remember every menu.