Rep Power: 0

My 2018 Si got totaled last fall (thanks, 16 year old driver who hit me from behind). I still have the spare key fob for it. I have since replaced the car with a 2021 Civic Sport that only came with one key fob.

Do the two fobs interchange? Is there a way to reprogram the elder key fob to work on the 2021, other than paying a locksmith a tidy sum, or springing for a key code device of my own?

I tried a couple of YouTube videos which claimed to work, but they did not work for me. I replaced batteries in both fobs to make sure that wasn't the reason. The 2021 fob has a button for remote start, which my new Civic doesn't have.



Photo: 2018 fob is at left.

 
Rep Power: 222

Dealer might be able to tell you

 
Rep Power: 512

likely it can be reprogrammed to the new car. Like Colin said (or rather implied), a dealership trip would be warranted to see if they can reprogram it

 
Rep Power: 0

I checked with a locksmith and he said, Honda changed the radio frequency the key fobs uses in 2019, so my 2018 fob can't be used on my 2021 Civic...but also he said he could get me one that will work.
I guess the dealership is my next stop.

 
Rep Power: 367

radio frequency different... that's basically a no. Did not know that, good info

 
Rep Power: 0

I've used that locksmith before, I don't think he was trying to trick me into buying a new fob that I don't need.
Did Honda really switch frequencies? No idea but...it would make sense if they did, since previous generations of the Civic were among the easiest cars to steal...and electronic key fobs were a measure to combat theft.
I am going to ask a Honda dealer about this, so I can hopefully get a second fob that I will likely never need, lol

 
Rep Power: 512

Definitely post up an update of what the dealership says. I'm curious about that

 
Rep Power: 0

Dealership confirmed, the fobs have different part numbers and DO NOT interchange. For a fob that will work on my 2021 Civic, and programming it, it would cost about $250. Dammit.
I'm going to try selling the 2018 fob to try and raise cash to put toward getting one that will work on my 2021.

 
Rep Power: 0

Dealership confirmed, the fobs have different part numbers and DO NOT interchange. For a fob that will work on my 2021 Civic, and programming it, it would cost about $250. Dammit.
I'm going to try selling the 2018 fob to try and raise cash to put toward getting one that will work on my 2021.

 
Rep Power: 0

The manufacturer part number for the 2018 fob is, A2C92005000.
The manufacturer part number for the 2021 fob is, A2C92005700.

To see which part number your OEM key fob is, remove the emergency key, gently crack open the fob using a coin, and inside you will find (in a tiny font) Continental then the part number. There will also be an FCC ID number but on the 2018 fob and the 2021 fob, the FCC ID number on the fob is the same.
I found and bought a used OEM fob with the right part number for $19. I am going to try reprogramming it using the YouTube video I mentioned before. I think it will work this time.
I listed my 2018 fob for sale on ebay for $25 free shipping.

 
Rep Power: 367

thanks for the additional info, hopefully it will help pothers in the future

 
Rep Power: 0

No problem, and you're welcome. If any of y'all want to buy my 2018 fob, it works, and has a brand new battery...just send me a message.

 
Rep Power: 0

And it sold already. I should have asked more!! A place that sells keys bought it.
If any of y'all have any key fobs you wish to sell, ask a good bit more than $25.