Add a key vs all keys lost — two different jobs
People use “key programming” for both, but they are technically very different. Adding a spare while a working key exists means the immobiliser can be opened with credentials it already trusts. All keys lost means there is no trusted credential in the car at all, so the security data has to be recovered from the vehicle itself.
One working key present. Usually OBD only, 20–45 minutes, no module removal, existing keys kept.
No key present. Requires entry, security data recovery and often bench or EEPROM access. 1–3 hours typical.
Treated as all keys lost with deletion: new keys written, old identities removed so a thief's key is dead.
Extraction from the lock, blade re-cut to code, transponder reused where undamaged — often the cheapest fix.
How a modern car key actually works
A car key does three separate jobs, and each can fail independently — which is why “my key doesn't work” is never enough information to quote from.
Cut to a code held against the VIN, or decoded from the lock wafers when no code is available.
A passive chip energised by the coil around the ignition. It answers a cryptographic challenge from the immobiliser.
Battery-powered rolling-code transmitter for central locking. Separate from the immobiliser identity.
Two-way LF/UHF communication with antennas in the body. The car locates the key before allowing start.
Encryption has escalated steadily: fixed-code chips in the 1990s, rolling-code and Hitag2 through the 2000s, then AES-class systems (Hitag AES, DST-AES, MQB, FEM/BDC, BDC2) from roughly 2013 onward. The newer the platform, the more likely the data lives behind a protected module rather than the OBD port.
OBD vs EEPROM vs bench — the three access routes
| Method | What happens | Typical use | Time |
|---|---|---|---|
| OBD | Key written through the diagnostic port with the car assembled | Most Ford, Vauxhall, PSA, Renault, Toyota, Nissan, older VAG/BMW | 20–60 min |
| EEPROM | Memory chip on a module read/written directly with soldered or clip contacts | Immobiliser boxes, older CAS, dashboards, ESL units | 1–3 hrs |
| Bench / boot mode | Module removed and powered on the bench to talk to the CPU directly | BMW FEM/BDC, VAG MQB, some Mercedes EIS | 2–4 hrs |
| Key learning by donor | Programmed spare key data loaded into a virgin key from recovered dumps | All-keys-lost where the module cannot stay in car | Varies |
An all-keys-lost job, step by step
- 1.Verify the vehicle and owner
Reg and VIN checked, proof of ownership confirmed, immobiliser system identified before travel.
- 2.Gain entry (if no key)
Non-destructive entry via lock decoding or picking; the lock is left working exactly as before.
- 3.Read the security data
Key data pulled via OBD, EEPROM or bench/boot access depending on the platform.
- 4.Cut and prepare the key
Blade cut to code or decoded from the lock; transponder prepared, virginised or cloned as the system requires.
- 5.Write and sync
New key written to the immobiliser, lost keys deleted where supported, adaptations kept intact.
- 6.Test everything
Crank, start, remote locking, comfort access and steering lock all verified before handover.
What key work should cost and how long it takes
| Job | Typical time | From |
|---|---|---|
| Spare transponder key, cut and programmed | 20–45 min | £120 |
| Spare remote / flip key | 30–60 min | £140 |
| Smart / proximity key added | 45–90 min | £180 |
| All keys lost, OBD-capable platform | 1–2 hrs | Quoted per VIN |
| All keys lost, bench or EEPROM platform | 2–4 hrs | Quoted per VIN |
| Broken key extraction and re-cut | 30–60 min | From £80 |
| Local Wolverhampton call-out | — | £15 |
Dealer routes are usually slower rather than simply dearer: a main dealer often needs the vehicle recovered in, an online security session booked and keys ordered against the VIN. Mobile programming removes the recovery cost and most of the waiting.
System-by-system: what to expect on your car
Add-a-key is often OBD. All keys lost on FEM/BDC generally means module out and bench work, then ISN alignment with the DME.
Older Immo 4/5 can be OBD or cluster EEPROM. MQB and MQB48 need component security data from cluster or ELV, often on the bench.
Key files are written after EIS read; ESL/ELV steering locks frequently fail alongside and are repaired or cloned at the same visit.
Broadly OBD-friendly including all keys lost, with security-timeout waits on some models. Efficient jobs with predictable pricing.
KVM/RFA modules hold key data; all-keys-lost commonly requires module access. Cloning a matched KVM is often the reliable route.
Mostly OBD with PIN calculation from the immobiliser; smart-key systems need the correct blank type by frequency and chip.
Not sure which system your car uses? The key coverage checker lists systems by make and model, and a reg or VIN lookup on the homepage gives us the build data we need to answer precisely.
Proof of ownership, and legitimate practice
Key work is security work. Any auto locksmith operating properly will ask for photo ID plus paperwork tying you to the vehicle — V5C, insurance, lease or hire agreement, or a purchase invoice. We also record the reg, VIN and keys issued for each job.
For a wider view of the trade — lockouts, extraction, immobiliser defence and relay-theft protection — read the full auto locksmith guide.
What to send us for an accurate quote
The VIN confirms build data, immobiliser type and blade code — the difference between an estimate and a price.
One working key, none but the car is open, or none and the car is locked. Each changes the method.
Blade with buttons, flip remote, or keyless proximity fob. A photo of the old key is ideal.
Postcode, whether the car is on a driveway, street or in a car park, and whether it moves under its own power.
Recent theft attempt, failed programming attempt, dead battery jump-start or a previously cloned key all matter.
ASAP, today or flexible — this sets the slot rather than the price.
Frequently asked questions
Q.How much does all-keys-lost key programming cost in the UK?
Add-a-spare transponder keys start around £120 and smart/proximity keys around £180. All-keys-lost is quoted per VIN because the work varies: an OBD-friendly Ford or Vauxhall is far quicker than a BMW CAS/FEM, Mercedes EIS or a VAG MQB cluster that needs bench or EEPROM access. Expect a range rather than a single number until the immobiliser system is confirmed.
Q.Can a key be made if the car is locked and no keys exist?
Yes. The door lock is decoded or picked non-destructively to gain entry, then the key is programmed as normal. Boot or glovebox locks are sometimes easier to decode than the door on certain models.
Q.How long does all keys lost take?
Typically 1–3 hours on site. Systems that need a module removed and bench-read (some BMW FEM/BDC, VAG MQB, Mercedes EIS/ESL) can take longer, and occasionally a module is taken away and returned the same day.
Q.Will my old lost keys still start the car?
On most systems the lost keys can be deleted so only your new keys work. Some older platforms allow only a full immobiliser re-sync, which achieves the same outcome. Always ask for lost keys to be removed if a set has been stolen.
Q.What proof of ownership do you need?
Photo ID plus a V5C, insurance certificate, hire/lease agreement or an invoice showing the vehicle. Legitimate auto locksmiths refuse work without it; anyone who does not ask is a red flag.
Q.Is a cloned key as good as a programmed key?
A clone copies an existing key's transponder, which is fast but leaves the lost keys live and cannot be deleted. A programmed key is written into the immobiliser as its own identity, which is the right choice for security and for keyless systems.
Q.Do you need to remove a module to make a key?
Not usually. OBD programming covers a large share of cars. Removal only becomes necessary when the security data is not accessible through the diagnostic port — common on protected BMW, VAG and Mercedes platforms.
Q.Can you program keys for vans and commercial vehicles?
Yes — Transit, Transit Custom, Sprinter, Vito, Crafter, Ducato/Relay/Boxer, Vivaro/Trafic and similar are routine, including all-keys-lost and locked-out entry.
Need a key today?
Send the reg, postcode and what has happened to the keys. We confirm the immobiliser system and price the exact vehicle before anyone travels.