It’s in the owners hand book, no diagnostic tool required. Manually unlock all the doors inside the car, remove the emergency lock cover on the outside passenger front door handle, using the emergency key blade from inside the key fob turn and hold the lock to the unlock position and press the unlock button on the fob then turn the key and hold in the lock position then press the lock button on the fob and it should re-synchronise the key fob to the car.