Key won't start the car, remote buttons dead, or a new key that the car simply ignores? New Forest Auto Locksmith carries out car key programming at your vehicle anywhere in the New Forest, coding transponder keys, remote fobs and smart keys with dealer-level diagnostic equipment.
Car key programming registers a key's electronics with the car, so the immobiliser lets the engine start and the remote locks and unlocks the doors. Almost every car built since the late 1990s needs it. A key can be cut perfectly and still be useless until its chip has been coded to that particular vehicle.
A modern key usually holds three separate pieces of electronics. The transponder chip talks to the immobiliser when you start the car, and needs no battery. The remote transmitter locks and unlocks by radio. On keyless cars, a proximity system lets the car sense the key nearby. Each may need its own pairing step, which is why car key coding sometimes fixes one function and not another.
Mobile car key programming means the equipment comes to the vehicle, on a driveway, at work or at the roadside. There's no need to tow a car that won't start, or to book it into a workshop for a job that takes under an hour on most vehicles.
Car not accepting the key? Call and describe what it's doing: 023 8218 2674Many keys that seem dead only need reprogramming. Others have failed and need replacing. The symptoms usually point the way.
| What the key is doing | Usually means | Usual fix |
|---|---|---|
| Starts the car, buttons do nothing (new battery fitted) | Remote has lost its pairing | Key fob reprogramming |
| Buttons work, engine won't start | Transponder not recognised | Reprogramming or new chip |
| Nothing works, case cracked or wet | Electronics damaged | Repair if possible, otherwise replace |
| Key worked until a battery or electrical repair | Programming lost | Car key reprogramming |
We test before quoting, so you're not sold a new key when the old one only needs coding again.
Knowing where a car stores its key data decides how the job is done. This is the part that separates a specialist from a key-cutting counter.
When you turn the key or press start, an antenna around the ignition or start button reads the transponder. The immobiliser compares it with its list of approved keys, and if it matches, tells the engine management that starting is allowed. Transponder key programming adds a new entry to that approved list.
On many vehicles, immobiliser programming runs through the diagnostic socket under the dashboard, using the manufacturer's own key-learning procedure. Some makes ask for a security PIN first, which our equipment can retrieve from the vehicle in most cases. Many Ford, Vauxhall, Nissan and Peugeot models are handled this way.
Some cars keep their key data in a dedicated security module that has to be read directly. Earlier BMWs use the CAS, later ones the FEM or BDC. Mercedes-Benz authorises keys through the EIS. Volvo uses the CEM, and Peugeot and Citroën the BSI. Ford uses the BCM or GEM depending on model, and many Volkswagen group cars hold immobiliser data in the instrument cluster, with some Audis using a module known as BCM2. Occasionally the module's EEPROM memory chip has to be read on the bench, and the original data is always backed up before anything is changed.
Smart key programming adds the proximity function on top of the transponder, so the car detects the key for hands-free entry and push-button start. On Volkswagen group cars this is the KESSY system. Every function is tested before we finish: start, remote locking and keyless entry.
Car key programming is priced per vehicle, because the procedure ranges from a short diagnostic routine to module-level work. Adding a key while one still works is usually at the lower end. Programming with no working key present, or on a vehicle that needs its security module read, takes longer and costs more. The price is confirmed before any work starts.
With a working key present, many cars allow a simpler procedure. With no key at all, the security system has to be accessed more deeply. If you've lost every key, see Lost Car Keys.
There's no payment upfront and no hidden charges. If diagnosis shows the car needs a different procedure from the one described, you'll hear the revised price first, with no call-out charge if you choose not to go ahead.
For a programming price, call: 023 8218 2674A car stops recognising its key when the transponder isn't authorised, the remote has lost its pairing, the key battery is flat, the reader antenna has failed, or there's a separate electrical or ignition fault. Programming fixes many of these, but not all, which is why the fault is diagnosed before anything is coded.
A flashing key or immobiliser light while the engine turns over usually means the car is not recognising the key's transponder. A dropped key can damage the chip, and some keys lose their coding after battery or electrical work.
If the engine starts but the remote won't lock or unlock, the fob battery or the remote pairing is the likely cause. Fit a fresh battery first. If that doesn't help, key fob programming usually restores it.
A weak fob battery often stops a keyless car detecting the key. Most have a backup spot, shown in the handbook, where holding the fob lets the car start anyway. If it still won't, the key or the car's receiver needs testing.
A failed antenna ring, a faulty module, a worn ignition barrel or a weak car battery can all look like a key fault. We'll tell you plainly what we find. If the ignition is the problem, see Ignition Repair.
If you need an extra key while yours still works, see Spare Car Keys. If the key itself is cracked, snapped or water-damaged, see Broken Car Keys. For keys locked inside the car, see Locked Keys In Car. The full range is listed on our Services page.
Our programming equipment covers most European, Japanese and Korean vehicles, including many imported Toyota and Nissan models, from key fob programming on basic remotes to keyless smart keys. A small number of very recent models can still only be coded by the dealer, and we'll confirm that before travelling.
This Land Rover Range Rover in Lyndhurst required key and immobiliser programming with the vehicle present, allowing the replacement to be matched and checked on site.
View job
This Suzuki Swift in Bransgore required key and immobiliser programming with the vehicle present, allowing the replacement to be matched and checked on site.
View job
This Nissan Elgrand in Cadnam required key and immobiliser programming with the vehicle present, allowing the replacement to be matched and checked on site.
View jobThese details help us tell a quick reprogramming job from a fault that needs diagnosing:
Mobile car key programming covers the whole New Forest, from Brockenhurst to Fordingbridge. You can also contact us online.
Send your details and we'll come back to you with a price. For anything urgent, calling is quickest.
Describe what the key is doing and we'll tell you whether it needs coding, repair or replacing — or request a quote online.
