Mercedes-Benz Car Key Replacement in Hamilton

Losing every key is a different job from cutting a spare. There is no original to read, so the new key has to be generated from the vehicle itself. On most Mercedes-Benz models we do that through the OBD port: the diagnostic tool talks to the immobiliser, authenticates, and writes a brand-new key into the vehicle's memory.

Where a model will not accept a new key over OBD — some older immobiliser boxes and a few later security modules simply refuse — we read the immobiliser or ECU memory directly, recover the key data held in it, and write a new key from that. That is EEPROM work, and it is done in the van at your vehicle rather than sent away. It is slower than an OBD job and priced accordingly, but it means an all-keys-lost Mercedes-Benz does not need towing to a dealer.

Mercedes changed its key security part-way through the 2010s, and the change matters more than the model or the mileage. Cars on the earlier FBS3 system — broadly up to 2014 — we handle in full: keys cut and programmed, all-keys-lost recovered, old keys deleted, at your vehicle.

From FBS4 onward, roughly 2015 and newer, the system is closed to everyone outside the franchise network. No independent locksmith can write a key to an FBS4 car, and anyone who tells you otherwise is guessing. If yours is FBS4 you need Mercedes themselves.

Ring us with the registration and we will tell you which system your car uses before you have paid us anything. We would rather say so on the phone than send someone out to give you the same answer.

Cutting you a new key does not stop the old one working. If a Mercedes-Benz key has been lost, stolen, or kept by a previous owner, the car will still start for whoever holds it until that key is removed from the immobiliser's memory.

Ask us to delete it and we de-register the missing key so it no longer starts the vehicle. It costs nothing extra while we are already programming a replacement, and it is the part most people do not think to ask for. Worth doing on any second-hand purchase where the seller could not hand over every key.

Not every Mercedes-Benz on Waikato roads was sold new here. Vehicles that arrived used from another market can carry a different immobiliser generation and a different key blank from the NZ-new version of the same model and year, even when the two look identical.

Remote frequency is the usual giveaway: vehicles built for New Zealand, Australia and Europe generally run at 433MHz, while cars built for other markets often sit elsewhere on the band. A remote bought online for the wrong market will not talk to the car even when the blade fits.

This is why we ask for the registration before we set off rather than just the make and model — it tells us which build the vehicle actually is, so we bring the right blank and the right equipment the first time.