Last updated: May 2026
Car Key Programming in Exeter
OBD and EEPROM programming for all systems — BMW FEM, Mercedes EIS, VW MQB and every major platform
Car key programming is the electronic process of pairing a key to your vehicle's immobiliser. Without it, a correctly cut key will turn in the ignition but the engine will not start. We carry out all programming methods across Exeter and Devon — from standard OBD diagnostic port access through to advanced EEPROM chip programming on the most security-intensive platforms in use today.
What’s Included
OBD vs EEPROM Programming — What’s the Difference?
Most car owners know their key needs ‘programming’ but do not know that there are fundamentally different methods — and that not every locksmith can perform both. Understanding which method your vehicle requires is the first thing we establish before quoting.
Why the method matters
OBD programming communicates through the vehicle’s standard diagnostic port using the car’s internal data network. It is fast, non-invasive and works well for most key programming scenarios where at least one working key remains, or where the vehicle uses an older or less restrictive security platform.
EEPROM programming is a completely different approach. It involves reading data directly from the memory chip inside the vehicle’s ECU, immobiliser module or key programming unit — either by connecting to the chip in-circuit or by physically removing it. This accesses the security-critical data that the standard OBD port either cannot reach or actively blocks access to.
The reason EEPROM is needed on modern high-security vehicles is deliberate: manufacturers such as BMW, Volkswagen and Mercedes introduced OBD security restrictions specifically to prevent unauthorised key programming via the diagnostic port. EEPROM access bypasses these restrictions at the hardware level.
The Thatcham Research vehicle security rating system grades immobilisers by how resistant they are to compromise — the higher the Thatcham category, the more likely EEPROM access is required for legitimate key replacement work.
Which method does my car need?
Call us with your registration number and we identify the correct approach in seconds. As a general guide: vehicles with one remaining key and standard security platforms typically need OBD only. All-keys-lost scenarios and high-security platforms (BMW FEM/BDC, VW MQB IMMO4/5, Mercedes EIS) almost always require EEPROM.
How It Works
Key Systems We Programme — Platform by Platform
Every manufacturer uses different security architecture. The same ‘key programming’ job has entirely different technical requirements depending on make, model and year. Here is what we work with across Devon.
Why Our Equipment Makes the Difference
Not all programming tools are equal
Generic OBD diagnostic tools are widely available and will programme keys on many common vehicles. But they have hard limits. On high-security platforms — BMW FEM/BDC, VW MQB IMMO5, Mercedes EIS — a generic OBD tool either cannot establish communication with the security module at all, or can connect but is blocked from accessing the key data it needs.
Specialist EEPROM equipment — the kind required for these platforms — is significantly more expensive and requires genuine expertise to use correctly. Reading the wrong address from an EEPROM, or writing incorrect data back, can cause serious problems that are expensive to correct. This is not work for generalists.
Our technicians hold IMI qualifications — the recognised standard for automotive technical competence in the UK — and work with specialist programming platforms that cover the full range of systems we encounter across Devon. We invest in equipment updates as new vehicle generations appear, because a tool that covered BMW CAS in 2018 may not cover BMW FEM in 2024.
Honest about edge cases
There are situations where even specialist independent equipment cannot complete the job — usually very recently released vehicle variants where no aftermarket solution yet exists. If your vehicle falls into this category, we will tell you before attempting anything. We do not attempt work we cannot guarantee, and we do not charge for unsuccessful attempts.
All Makes Covered Across Devon
We programme keys for all major makes across Exeter and Devon. The most technically demanding work we see regularly is BMW FEM/BDC replacement across Exeter city and East Devon, VW MQB all-keys-lost (particularly Golf Mk7 and Mk8 which are common across the Exeter student and commuter population) and Mercedes EIS work across the broader Devon area. Ford Transit programming — particularly all-keys-lost on commercial vans — is among the most frequent commercial jobs across Marsh Barton and Exeter’s trading estates.
Mobile Key Programming Across Exeter and Devon
We carry out key programming at your location — home, workplace, car park or roadside. The diagnostic equipment and programming tools travel with us in the van. Based near Honiton in East Devon, we cover Exeter city centre, all surrounding suburbs and the wider Devon and Somerset area. For planned spare key work we can book a convenient time; for emergencies we respond immediately.
Frequently Asked Questions
What is the difference between key cutting and key programming?
Key cutting shapes the physical blade so it operates the vehicle’s mechanical lock. Key programming is the separate electronic step that registers the key’s transponder chip with the vehicle’s immobiliser. A correctly cut key with no programming will turn in the ignition but not start the engine. Both steps are required for a complete working key — we carry out both in a single visit. See our guide: transponder car keys explained.
Can you programme a key I bought online?
Sometimes, but it depends. Online key blanks vary widely in quality and specification — many are not compatible with the exact security variant of your vehicle even when listed as compatible. We always recommend letting us source the correct blank, as a failed programming attempt due to an incompatible blank wastes time and, on some systems, uses up a programming attempt that cannot be recovered. If you do bring your own key, we will assess compatibility before attempting anything.
What does all-keys-lost programming involve?
All-keys-lost programming means generating a new key with no reference key present. This requires reading security data directly from the vehicle’s ECU or immobiliser module using EEPROM programming — a process that bypasses the OBD port entirely and accesses the memory chip directly. It is more involved than standard programming and requires specialist equipment, but it means we do not need a recovery truck or a dealer appointment. We carry out all-keys-lost replacement regularly across Devon for all major platforms.
How do I know if my car needs OBD or EEPROM programming?
In most cases you do not need to know — we identify the correct method from your vehicle registration. As a general guide: if you have at least one working key and a mainstream vehicle, OBD is likely sufficient. If all keys are lost, or your vehicle uses a high-security platform (BMW FEM/BDC, VW MQB IMMO5, Mercedes EIS), EEPROM is required. Thatcham Research grades vehicle immobiliser systems by security level — the higher the grade, the more likely EEPROM access is needed.
Can you programme proximity keys with push-button start?
Yes — proximity key programming (BMW Comfort Access, Mercedes Keyless Go, Land Rover KESSY, VW Kessy) is a significant part of our work across Devon. A proximity key requires programming of both the standard immobiliser pairing and the proximity entry function. Both are completed in a single visit. We do not programme immobiliser only and leave the proximity non-functional.
My newly programmed key does not work — what has gone wrong?
Several possibilities. The most common: the key blank is incompatible with the vehicle’s specific security variant; the programming was completed against the wrong module; or an antenna fault is preventing the programmed key from being recognised. We diagnose all three on site. If a key we have programmed does not work before we leave, we identify and resolve the cause — we do not leave until the key is fully functional. See our immobiliser diagnostics service for more complex underlying faults.
Do you programme keys for commercial vans?
Yes — commercial van key programming is a regular part of our work across Devon, particularly around Marsh Barton industrial estate and Exeter’s trading areas. We programme keys for Ford Transit (all PATS generations), Mercedes Sprinter, VW Transporter (T5 and T6), Vauxhall Vivaro and all other major commercial makes. For businesses running fleets, a single working key on a van is a significant operational risk.
How does key programming by an independent specialist compare to a main dealer?
For the vast majority of vehicles, the end result is functionally identical. Both an IMI-qualified independent specialist and a main dealer produce a fully programmed key that starts the vehicle and operates all functions. The difference is in cost, speed and convenience — not in quality. There are genuine edge cases where dealer-only programming tools are needed (very new models, some manufacturer-specific variants), and we will tell you honestly if your vehicle falls into that category. See our full comparison: auto locksmith vs main dealer in Exeter.
Speak to a Specialist
Tell us your make and model. We confirm the programming method and fixed price immediately. No jargon, no guessing.