Key won't pair with used ECU?

Hi...my shop just replaced my ECU (they put a used one in), and they're saying they can't get my 2 keys to pair with it. The keys work just fine physically in the door locks and ignition, it's just the remote buttons don't work. Also to note, the 2 keys had stopped working even before I took it in, no idea why. They're saying I would need to purchase new keys to pair with the newly-installed ECU...is this truly correct?? Can you not pair older keys with a different ECU? Thanks for your help.

U need the keys, ecu and imobilizer from the same car to get it to start. If u send everything to ecudoctors in FL they can reprogram everything. I know the dealer can do reprograms on certian things too.

If you end up needing it, I have DME, Keys, all Locks, Alarm unit and Immobilizer available.

@Kris, thank you very much for your offer, but I think I'm good. @De Jeeper, as mentioned, they installed a new (used) ECU...so it appears I already have a problem in that things aren't from the same car. If in fact I were to buy a new replacement key from Porsche, could that be programmed to work in my situation? I didn't know if new keys are like a blank slate that can be programmed to work with anything?

Oh boy...basically this is the way it works. Keys with the appropriate key code tag are what you need. The dealer uses the key code tag to program the key to the immobilizer. There are five key code slots in the immobilizer. Since the cars are delivered with three programmed keys, the two regular keys and one valet key, three slots in the immobilizer are already taken. On a used immobilizer then there are only two open key code slots left. Maybe in your case someone already took up the fourth key code slots so only one new key can be programmed. Remember this - the keys are programmed into the immobilizer. The keys themselves are not programmable. Thus the necessity when buying new keys that they come with the key code tag, that is in turn programmed into the immobilizer. The car reads the key via a RFID surround at the ignition switch. The car reads the key embedded RFID code on a pill inside the key case. The immobilizer reads the RFID code and tells the DME/ECU with a handshake...yes..this is the correct key to start the car. Nothing else will work.

Thank you so much for the comprehensive info. To my knowledge (I'm the third owner of the car), the immobilizer is the original one...so assuming no other keys were ever programmed to it, it would seem there should be 2 slots still available. Again, just guesses and assumptions here. One last question: Is there any way to recover the key code tag info from the old keys that I have? I didn't know if a dealership was able to do this.

"One last question: Is there any way to recover the key code tag info from the old keys that I have? I didn't know if a dealership was able to do this." Nope. Impossible. Not even Porsche has that information.

You stated the two keys weren't working before the ECU swap , why do you think they would work now ? Do you still have the original ECU ? If I were you I would call ECU Doctor in Florida and discuss your situation with them .

Quotes source post: 18270959

This.

I myself had no idea about how everything worked together. My assumption was that once they got the new ECU they could simply reprogram the keys...but obviously I've now learned via this thread that that's not possible. Maybe more problematic was that the shop that's working on this said they were "unable to pair the keys": If the keys/ECU/immobilizer all need to be from the same car, then the shop should have known this and never spent time on it...which I'm guessing they'll try to charge me for.

What problem was the shop trying to correct with the ECU swap ? Do they/you still have the original ECU ?

My car was having nightmares starting up. They'd supposedly diagnosed and ruled everything else out, hence the ECU swap was their last resort. (Honestly nauseous about the whole experience, I'm just trying to get the car back and be done with it.) I did ask that they keep my old ECU though, as I'd like it back...just to have, or possibly to have independently diagnosed.

Well i say it again, send it all to ecudoctors. They can fully test the dme for $99. Send the the keys, imobilizer and the dme so u can stop waisting $.

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I think at this point the above suggestion is the best path forward .

Robbie, IMHO, you should reinstall the ECU and get the car to a dealership if the goal is to get functioning keys. As Joe has clearly noted, the process is very intensive and involves a very strict procedure to match new keys to the ECU. Since you said the original keys worked to start the car with the original ECU, then that would tell me that the RFID pill inside the key fobs are working. It's just the electronic board inside the fob that has gone bad. The board is responsible to remotely unlocking/locking the car. Sometimes, the dealership can reprogram the keys to be work again, but in most cases replacement is the only option. ECU doctors is probably the only other reliable solution that is well established here in the RL community. Here is the procedure to program a new replacement immobilizer (Porsche calls it a KESSY/PAS) as listed in the shop manual. Reading the steps, you can get a sense of the process of learning keys into the car's security system.

Yeah, what he said ^^^

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Thank you again for everyone's help. I finally just got the car back two days ago, so first priority if drive cycle to get it smog-checked before I get ticketed for expired plates on Monday :/ Once that's taken care of, I'll go about working on the keys. Thanks again

Very interested in how you resolve this vetfever

Was this ever resolved? I had my ecu swapped a while ago and only have one working key, purchased a second key fob from Suncoast so I had the tags but the dealer here tired and couldn't get it to program and said the need to do a deep diagnosis (which means money). Can a reader see if all the slots are full, if they are does that mean I'm sol?

Never resolved, but I also didn't end up putting much time into it as it didn't look promising. YMMV

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A P1/P2/P3 can see if there are available slots if all the slots are full they can overwrite one of them. As a guess perhaps someone changed the alarm unit and DME in your car and as such the IPAS code to your car no longer matches... The only thing the dealership could possibly do is read out the VIN from the modules and try the matching IPAS codes. It really depends on if there were able to see the remote or transmitter list or if they were able to see the list and then they could still not code the transmitter or remote. This all happens in the alarm module not the "ECU".