Question 1

Do I need to bring my 2015 Audi S5 to a shop for key replacement?

Accepted Answer

No. I come to wherever your car is parked, whether that is your driveway, your office, or a parking lot near the Ventura Botanical Gardens area of Ventura. I carry the key blank, the HU66 cutting setup, and the BCM2-compatible programming hardware in the van. The Audi dealer requires you to either drive in with a working key or get the car towed to their service bay. One owner on AudiWorld found out the hard way that without a working key the car will not shift out of Park, making flatbed towing the only option. I handle everything on site and you keep your vehicle the whole time.

Question 2

How does the mobile key replacement process actually work on my S5?

Accepted Answer

You call, give me year, make, model, and VIN. I confirm your key type and quote you on the phone. When I arrive, I decode your door lock with the HU66 Lishi to map the wafer positions in the VAG keyway, then cut the new flip key blade on site. The Megamos 48 CAN transponder gets programmed through the OBD-II port using BCM2 adapters that talk to the immobilizer module. I sync the remote functions, test ignition start, all door locks, and trunk release. The whole thing happens next to your car. No tow, no waiting room, no second trip.

Question 3

What do I need to have ready when you show up?

Accepted Answer

Your vehicle, a valid photo ID, and proof of ownership like registration. That is it. I pull the VIN from the dashboard or door jamb to verify the key specs against Audi's system. The dealer sometimes requires additional steps, including VIN-based ordering through Audi headquarters and verification of how many keys are coded to your ECU. Some CPO buyers on the Audizine forums have found out they never received the original key code card (the plastic wallet card with the mechanical cut code) and had to go back to the selling dealer just to get one reissued. I skip all of that.

Question 4

My 2015 S5 says "Immobilizer active" or "Key not recognized" on the dash. Is the key dead?

Accepted Answer

Not always. The Megamos 48 CAN transponder in these keys can lose sync with the BCM2 module after a battery disconnect, a dead vehicle battery, or a failed software update. Owners on Audizine report seeing "Immobilizer See Dealer" in the instrument cluster after jump-starting with low voltage. Before assuming the key failed, check your vehicle battery. A weak battery can cause the BCM2 to drop the transponder handshake mid-crank. If the battery tests fine and the message stays, the key's transponder may need reprogramming, which I can do on site through the OBD port.

Question 5

I lost every key to my 2015 S5. Can you still make a new one?

Accepted Answer

Yes, but it takes longer. All-keys-lost on the B8.5 S5 means the BCM2 module (board with the 4H0 907 064 prefix number) has to be physically removed from behind the dash, opened, and bench-read to extract the encrypted key data. That step alone adds one to three hours depending on access and read time. Once the dump is pulled, I can generate a new working key, program the transponder, and code it back in. Plan for a two-to-four-hour visit instead of the usual 35 minutes. It still saves a good chunk over the dealer and you do not need a tow.

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