Smart Key Replacement Worthing, Keyless Fobs Coded at Your Car

A smart key, also called a proximity key or keyless fob, never goes into a lock or an ignition. The car senses it nearby, unlocks when you touch the handle and starts when you press the button. Replacing one means supplying a matching fob and coding it to the car so the car accepts it as its own. It is the keyless branch of car key replacement, and the most technical key most Worthing drivers carry.

Some cars have keyless start only, where you still press a button on the fob to unlock. Others have full keyless entry as well, where the doors open by touch. The replacement fob has to match the system your car was built with, and the registration is enough to check which one it is.

Three kinds of key look alike in the hand and work very differently. The one your car uses decides the job, the time and the cost.

If your car uses a button fob rather than a smart key, see replacement key fobs instead.

Mercedes-Benz brought the first smart key to market as Keyless Go on the S Class in 1998. The same idea is now used by almost every maker.

Antennas in the door handles and the cabin send out a short range, low frequency signal. The fob wakes up, answers with its own code by radio, and the car unlocks only if the code matches one it has stored.

Inside the car, the cabin antennas check the fob is inside and not just near the door. Only then does the immobiliser release and the start button work.

Because the car checks the fob every time, a new fob has to be added to the list of fobs the car trusts. A fob that is only cut and never coded will open the door with its blade and do nothing else.

Each maker gives its keyless system its own name. The name in your handbook tells you that the car uses a smart key, and which kind of fob to supply.

Some makes have their own pages, Mercedes key replacement, BMW key replacement and Ford key replacement, and the rest are listed under the car makes we cover.

Proximity key programming uses diagnostic equipment plugged into the car to add the new fob to the keyless system and the immobiliser. It is the same kind of work as car key programming, with one more system to satisfy.

With a working fob, the new one is added alongside it. This is the quickest and cheapest route, and it is worth doing as a spare car key before the last fob goes.

With no working fob, the car data is read to make and code a new one. On many newer keyless cars this is the hardest job a locksmith does, so the make, model and year are checked on the call before anyone sets off. The wider steps are covered under lost car keys.

A lost fob can still open a keyless car if someone finds it near the car. When fobs are lost or stolen, they are removed from the car at the same visit, which is the step described under a car immobiliser reset.

Smart keys cost more than any other everyday car key, because the fob holds more electronics and the coding reaches two systems. These are typical UK figures.

The price for your car is agreed in writing on the call, once the make, model, year and key situation are known.

Four things move the price of a smart key more than anything else.

A keyless fob for a family hatchback costs far less than one for a premium car, and some of the newest systems are dealer only.

Adding a fob to a car that already has one costs less than an all keys lost job, which needs more time and more steps.

A fob that handles entry and start carries more parts than one for push button start alone.

A late night or weekend visit can cost more, and that is said on the call, not at the car.

Every smart key hides a small metal blade for the day the battery dies. Knowing where it is saves many call outs.

A catch on the fob releases the blade. On many cars the driver door lock sits under a small cover at the end of the handle, which lifts off to reveal the lock. If the fob is inside a locked car rather than flat, the job is locked keys in car instead.

Hold the fob against the start button, or the spot the handbook marks, and press the button. A coil in the car powers the chip for just long enough to start.

Most smart keys use a coin cell such as a CR2032, reached by sliding out the blade and opening the case. A new battery is the first thing to try when the car stops finding the key.

A key not detected warning does not always mean the fob needs replacing. These are the usual causes and what fixes each one.

Smart keys are sold cheaply online, and it is tempting to buy one and have it coded. It can work, but check before you buy.

Many smart keys lock to the first car they are coded to, so a used key often cannot be coded to a second car. Some makes allow a key to be reset. Send the part number before buying.

Copies of the original fob vary in quality, from range to battery life. A fob supplied for the job is checked against your car before the visit.

A fob that looks right can be built for a different market or model year. The part number on the back of the original, or the registration, settles it.

Relay theft uses two devices to pass the signal from a fob inside the house to the car on the drive, so the car opens and starts. In one European test of 237 keyless cars, 230 of them could be opened this way.

Some newer fobs from Audi, BMW, Ford and Volkswagen go to sleep when they stop moving. Some fobs sleep after a minute or two and others take 15 or even 30 minutes, so it is worth checking the handbook for yours.

Keep fobs away from the front door, store them in a signal blocking pouch, and check the handbook for a way to switch keyless entry off. A visible steering wheel lock adds another barrier.

Newer vans such as the Ford Transit Custom and the Mercedes Sprinter are often sold with keyless start. Their fobs are coded the same way as a car fob, and van keys in general are covered under van key replacement.

Every smart key job starts with the registration, because the car decides the fob.

Smart keys for these makes are coded at the car. Newer models are confirmed on the call.

Smart keys are coded at the car across 15 towns and districts in BN11 to BN17, BN43, BN44, BN5 and RH20. Arrival times for each town are listed under areas we cover.

The questions asked most about smart keys, from cost and lost fobs to flat batteries.

Have the registration ready and say whether any fob still works. The price is agreed in writing before a van leaves.