BMW & MINI Key Fob Replacement: CAS, FEM, BDC by Chassis

BMW key fob replacement is decided by the immobilizer module in the car, not the model name: CAS1 on the 2002–2008 E65 7 Series (FCC ID LX8766S), CAS3 on 2003–2012 E-chassis 3 and 5 Series (KR55WK49127, HITAG 2 / 46 chip), CAS4 / CAS4+ and early FEM on 2009–2016 F-chassis cars (YGOHUF5662, HITAG PRO / 49 chip), FEM / BDC on 2014–2018 2 Series, 5 Series, X5 and MINI F55 / F56 (NBGIDGNG1), and BDC2 / BDC3 on 2015–2020 G-chassis cars (N5F-ID21A). Match the FCC ID and chassis code, confirm 315 or 433 / 434 MHz on the existing key, and program with a tool that supports that module — CAS3 add-a-key is an OBD job, while FEM / BDC and G-series work often means reading the ISN or a bench session. Car Key Source stocks aftermarket smart keys for each generation, one genuine OEM N5F-ID21A key for 2015–2021 G-Series and F-Series cars, the Lonsdor BM3S-01 universal board for G-chassis BDC2 / BDC3 cars, and the Original Lishi HU92.

How do I identify a BMW key by chassis and immobilizer?

BMW technicians talk in chassis codes (E60, F10, G30) and locksmiths in immobilizer modules (CAS, FEM, BDC). Neither is printed on the fob, so work from the FCC ID and part number on the back of the customer's key, then confirm against the model year. With no key, your tool identifies the module on the OBD port and the VIN decodes the chassis.

One catch: the CAS3 fob family carries several FCC IDs (KR55WK49127, KR55WK49123, KR55WK49186) for the same 3-button board across model years, so match the part number 6986583 rather than one FCC string.

Which BMW models use which key?

• LX8766S (2002–2008): E65 / E66 7 Series only, CAS1.
• KR55WK49127 (2003–2012): 3 Series (E90 family), 5 Series (E60), X5 (E70) on CAS3. Three buttons, 315 MHz.
• YGOHUF5662 (2009–2016): F-chassis 3, 5, 6 and 7 Series on CAS4, CAS4+ and early FEM. Four buttons, 315 MHz, in standard, red and blue shell variants.
• NBGIDGNG1 (2014–2018): 2 Series, 5 Series and X5 on FEM / BDC, 433 MHz, PN 9337240-01 (cross-references BMW 6805990-01 and Hella 5FA 011925-33). The MINI F55 / F56 version is a 3-button fob, PN 9367409-01, at 434 MHz.
• N5F-ID21A (2015–2021): G-chassis cars on BDC2 / BDC3, 434 MHz, PN 9395329-05. The aftermarket row is listed for 2015–2020 in silver; the genuine OEM row is listed for 2015–2021 X3, X4, X5, X6, 5, 6 and 7 Series.

See the BMW make page and the FCC pages for YGOHUF5662 and NBGIDGNG1.

What keyway and Lishi tool does a BMW use?

E-chassis BMWs and R-series MINIs use the HU92 two-track keyway. The Original Lishi HU92 2-in-1 pick and decoder reads the ignition on every listed BMW, MINI and Land Rover vehicle and the trunk, but door reading is limited to vehicles up to 2006 because BMW changed the door wafer arrangement after that. F- and G-chassis cars use a different profile for the emergency blade; verify on the vehicle before you cut. On a smart-key BMW the blade only opens the door — programming, not cutting, is the job.

Aftermarket or genuine OEM on a BMW?

BMW is the make where a customer is most likely to ask for a genuine key, and there is one genuine OEM row in the catalog: the OEM 4-button smart key for BMW G-Series and F-Series 2015–2021, FCC ID N5F-ID21A, PN 9395329-05, on HITAG PRO NCF2951 / ID49 at 434 MHz and listed for the X3, X4, X5, X6, 5, 6 and 7 Series. The aftermarket N5F-ID21A row covers the same FCC ID and part number for 2015–2020 and is described as an original PCB in an aftermarket silver shell, so the choice is between a factory-finish fob and a lower-cost one with the same electronics.

Every other BMW and MINI row is aftermarket, graded AM. All of them are listed against the vehicles they program to, so the programming guarantee applies: if a key or remote won't program on the vehicle we listed it against, it is refunded within 30 days of delivery and we pay the return freight — the vehicle must match the listing and the part must come back resaleable. For the general trade-off, see aftermarket vs genuine OEM car keys; the full genuine OEM range is on the OEM hub.

How is a BMW key programmed?

Programming effort scales with the module generation; quote accordingly.

1. CAS1 / CAS2 / CAS3 (2002–2012): Add-a-key and all-keys-lost are OBD jobs on most professional tools (Autel IM608 family, Lonsdor K518, Xhorse VVDI2 / Key Tool Plus, Yanhua ACDP). CAS3+ with the later ISTAP firmware may require a downgrade or a bench read before the key can be made; your tool will tell you.
2. CAS4 / CAS4+ (2009–2016): Add-a-key is possible by OBD on many tools. All-keys-lost usually needs the ISN from the DME or a CAS4 bench read, which means a longer job and the right adapters.
3. FEM / BDC (2012–2018): Add-a-key on current tools is typically an OBD job with a module backup and a short programming sequence on the FEM / BDC itself; all-keys-lost adds a DME ISN read. Budget more bench time than a CAS3 car.
4. BDC2 / BDC3 G-chassis (2015 on): Coverage varies by tool and firmware. Some tools handle add-a-key by OBD with the ISN; others require a bench session. Check the tool's supported-vehicle list for the exact chassis and build date before you take the job.

Two rules that hold across every generation: keep the vehicle on a stable power supply for the whole session, because a voltage drop mid-write on a FEM or BDC can leave the module needing recovery, and confirm the fob's frequency (315 versus 433 / 434 MHz) against the existing key before you open the packaging. See how to program a key fob for the general workflow.

When is the Lonsdor BM3S-01 the right board?

The Lonsdor BM3S-01 universal smart key PCB is engineered specifically for BMW G-chassis vehicles on BDC2, BDC3 and select BCP immobilizer systems. It is a four-button, adjustable-frequency board generated on Lonsdor equipment and fitted into a BMW-style shell. Use it when your Lonsdor tool covers the G-chassis job and you would rather hold one board than separate frequency variants. Do not buy it instead of the vehicle-specific N5F-ID21A fob if you run Autel or Xhorse only — a universal board without the matching tool is dead stock. The trade-off is covered in universal remote or vehicle-specific fob and the Lonsdor board guide.

What Car Key Source stocks for BMW and MINI

All vehicle-specific rows below are aftermarket (AM) except the genuine OEM N5F-ID21A key, marked as such.

In-stock orders placed by 4 PM ET (Mon–Fri) leave the warehouse the same business day. US orders ship from our Florida warehouse; Canadian orders ship from Ontario — nothing crosses the border, so there is no customs, duty or brokerage for the buyer. Trade pricing is unlocked with an approved wholesale account — most applications are approved instantly; apply here. If the BMW you need is not listed, use the sourcing request path with the FCC ID and chassis code.

FAQ

Can a locksmith program a BMW key fob, or is it dealer only?

A locksmith with a current professional tool can program most BMW keys. CAS1 through CAS3 cars are routine OBD jobs; CAS4, FEM / BDC and G-chassis cars are covered by tools such as the Autel IM608 family, Lonsdor K518, Xhorse VVDI and Yanhua ACDP, though all-keys-lost often needs an ISN read or a bench session.

What is the difference between CAS, FEM and BDC on a BMW?

They are successive generations of the BMW immobilizer and body module: CAS (Car Access System) on E-chassis and early F-chassis cars, FEM / BDC on later F-chassis cars, and BDC2 / BDC3 on G-chassis cars. The generation determines the chip in the fob (HITAG 2 / 46 on CAS3, HITAG PRO / 49 on CAS4 onward) and how much of the job can be done by OBD.

Is the MINI Cooper key the same as a BMW key?

The 2014–2018 F55 / F56 MINI uses the same FEM / BDC system and the same NBGIDGNG1 FCC ID as the 2014–2018 BMW 2 Series, 5 Series and X5, but in a 3-button MINI shell with its own part number, 9367409-01, at 434 MHz. Order the MINI row for a MINI.

Does Car Key Source stock a genuine OEM BMW key?

Yes, one: the genuine OEM 4-button smart key for 2015–2021 BMW G-Series and F-Series, FCC ID N5F-ID21A, PN 9395329-05, at 434 MHz. Every other BMW and MINI row is aftermarket and is described as such.