Locksmith in Aventura, FL: Smart Keys, Push-to-Start and Every Lock, 24/7

A proximity key does two separate jobs. Its radio side, powered by the coin cell, tells the car the key is nearby so the doors unlock and the start button works; this is the passive entry, passive start system, PEPS. Its transponder chip, the immobilizer side, needs no battery: a coil in the backup reader powers it at very short range. That is why the backup position in the table above starts a car whose fob is dead, and why it makes such a clean test.

If the backup start works, the fault is power. Replace the cell, and if the remote still does nothing, check three things: the cell in upside down, a CR2025 where a CR2032 belongs, or a contact spring bent away from the cell. A car that later forgets the remote after a new cell is a pairing problem, not a battery one.

If the backup start fails as well, interference comes next. Nissan's bulletin on keys not detected names RF interference, with RFID tokens, several keys on one ring, a weak fob battery, RFID-blocking pouches, phones and chargers as contributors, and its owner manual warns that a second registered key or a toll transponder on the same ring can block the start. Move everything else away from the key and try again. BMW documents a different case on 5 Series cars built from March 2018: static discharge can put the key into a deep sleep, and pressing any button on it, or taking the cell out and refitting it, wakes it up.

When the key is fine, the car can be the cause. On the 2014 Jeep Grand Cherokee, Jeep's bulletin ties a "Key Not Detected" message to the RF hub module, cured by reprogramming it, and BMW traced a 3 Series whose Comfort Start failed while the car still started at the emergency spot to an interior antenna wire shorting against a metal bracket. The module side of that work is done at the car with dealer-level software under NASTF VSP; see module programming. If both fobs quit on the same day, suspect the car side first: the receiver, the BCM, a fuse or an aftermarket alarm.

And sometimes it is the fob. A fob that is physically sound but no longer paired is re-registered to the car. A wet or cracked fob is replaced with a new one, and a fob that keeps dropping out gets swapped for a brand-new one carrying the 4Keys warranty, the case set out in the deprogrammed or broken fob guide and on the Miramar page. On a Nissan, registering one Intelligent Key erases the others, so every key you want to keep has to be at the car, up to four. A fob you already purchased online can be used when its FCC ID, frequency and part number match, as the Kendall page explains. Service: smart key fob programming.

A condo or house lockout is opened by picking the lock first, whether it is a lever set, a deadbolt or a keypad whose batteries went flat. A key that is gone for good is dealt with on that visit by repinning the cylinder, so whoever finds it cannot use it; the front door, the back door and the storage room can all be set to open with a single key. In a building that runs a master key system, check with management before the unit cylinder is changed.

Worn locks are replaced with hardware that fits the holes already in the door, deadbolts are added where a door has only a knob, and keypad or app deadbolts are installed with their codes set. Restricted-keyway cylinders keep copies under control on any door that needs it. More on residential locksmith service, and night calls on emergency locksmith service.

Medical and professional offices get the business side. After a staff change, every cylinder the departing key opened is rekeyed. A master key system gives each manager the doors they need and one key to the owner, cut on restricted blanks. Card and fob readers let a credential be switched off on the day someone leaves, exit devices let people out with one push while keeping the door locked from outside, and the hook-bolt locks on glass entry doors are repaired or repinned. A business lockout after hours is answered at any time. See commercial locksmith service.