BMW Key Replacement & Programming — Mobile Service Across Somerset & Wiltshire
CAS, FEM or BDC — we handle whichever system your BMW uses, at your vehicle rather than at a dealership.
On a BMW, a key problem is very often a module problem. The car controls key recognition through a dedicated immobiliser unit, and which unit that is depends entirely on the generation in front of us.
We work across both the older CAS-based cars and the current FEM and BDC systems, diagnosing where the fault actually sits before any key is replaced.
Older BMW key systems we work on
CAS (Car Access System) is BMW's own name for their electronic immobiliser control unit, and its failure is a well-documented issue across several generations.
- CAS2 — E60/E61 5 Series and E63/E64 6 Series, 2003-2007
- CAS3 — E90/E91/E92/E93 3 Series, E87/E81 1 Series and E70 X5, 2005-2010
- CAS3+ — F30, F10 and F20 series, 2009-2014
- Symptoms include a 'Key Not Detected' or 'Key Invalid' message, no-crank no-start, and the key's code falling out of sync with the engine computer
Current BMW models we work on
On newer F-series and G-series BMWs the same job is handled by different hardware, and the symptoms look similar on the dashboard.
- The FEM (Front Electronic Module) or BDC (Body Domain Controller) handles this function rather than CAS
- The most common current-generation symptom is a 'Key not recognised' or 'Key not detected' dashboard message even with a known-good key fob battery
- Comfort Access touch-to-unlock functions can fail independently of whether push-button start still works
What happens on the visit
We read the vehicle first to establish which immobiliser system is fitted and whether the fault sits with the key or the module. Replacement keys are supplied and coded on-site, keys you no longer hold can be removed from the system, and everything is tested before we leave. Free quote before we arrive.
Common questions
- What is CAS on a BMW and why does it stop the car starting?
- CAS (Car Access System) is BMW's own name for their electronic immobiliser control unit. Its failure is well documented across CAS2 on the E60/E61 5 Series and E63/E64 6 Series from 2003-2007, CAS3 on the E90/E91/E92/E93 3 Series, E87/E81 1 Series and E70 X5 from 2005-2010, and CAS3+ on the F30, F10 and F20 series from 2009-2014. Symptoms include 'Key Not Detected' or 'Key Invalid', no-crank no-start, and the key's code falling out of sync with the engine computer.
- My newer BMW says 'Key not recognised' but the fob battery is fine.
- On newer F-series and G-series BMWs the immobiliser function is handled by the FEM (Front Electronic Module) or BDC (Body Domain Controller) rather than CAS. The most common current-generation symptom is exactly that message with a known-good fob battery, so the module side needs checking rather than the key being replaced on a guess.
- Comfort Access has stopped working but the car still starts.
- That is a recognised pattern on current-generation BMWs — Comfort Access touch-to-unlock functions can fail independently of whether push-button start still works. It points to the same FEM or BDC side of the system rather than to the ignition.
Where we regularly carry this out
See every area we cover across Somerset, Wiltshire and Dorset, or browse all our locksmith services.
BMW key or immobiliser fault today?
Free quote before we arrive — tell us the vehicle and we will confirm what is involved.
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Standard Payments
All major cards and contactless accepted on-site via mobile card reader.