Continental Automotive Smart Key Fob KR55WK4 – PCF7952 | 315 MHz

By Mohammad H. Abdelhadi, ALOA-Certified Master Locksmith, mobile automotive locksmith. Reviewed by Ray Obar, Master Locksmith. Updated June 1, 2026.

Fitments for the Continental Automotive Smart Key Fob (FCC ID KR55WK4) span a wide range of Nissan and Infiniti platforms, including the Nissan GT-R (2007–2024), Nissan Altima (2007–2012), Nissan Maxima (2009–2014), Nissan Murano (2009–2014), Infiniti EX (2007–2013), Infiniti FX (2009–2017), Infiniti G Line (2007–2015), and Infiniti Q60 (2014–2015). Across these vehicles, the fob handles passive keyless entry and push-button start over a 315 MHz RF link, paired with a PCF7952 transponder for immobilizer authentication. Each Continental Automotive Smart Key Fob (FCC ID KR55WK4) communicates with the vehicle’s body control module during a rolling-code handshake that validates the key before the engine will crank. Owners replacing the device should expect a dealer- or locksmith-level programming procedure, as this smart key requires on-board diagnostics equipment to register to the vehicle. When ordering a Continental Automotive Smart Key Fob (FCC ID KR55WK4), confirm that the FCC ID, frequency, and blade profile match the original unit.

Technical Specifications of the Continental Automotive Smart Key Fob (FCC ID KR55WK4)

The KR55WK4 operates at 315 MHz, which is the standard North American frequency for Nissan and Infiniti proximity-based keyless entry systems. Inside the housing, a PCF7952 transponder chip manages both the remote-control RF functions and the passive immobilizer challenge-response sequence. This dual-purpose architecture means the chip handles keyless entry commands at the 315 MHz carrier frequency and also responds to the low-frequency 125 kHz interrogation signal from the vehicle’s antenna coil ring when the fob is brought close to the start button or steering column.

The mechanical emergency blade uses the NSN14 keyway profile, a high-security sidewinder cut found across many Nissan and Infiniti models from this era. The NSN14 blade allows manual door entry and, on some models, steering column lock release in the event the fob battery is depleted. Locksmiths cutting the emergency blade will need an appropriate high-security key machine capable of milling the internal track pattern characteristic of the NSN14 profile.

Vehicle Compatibility Details

The validated fitment list for this smart key covers two distinct marques under the Nissan Motor Company umbrella, spanning nearly two decades of production years. On the Nissan side, the GT-R uses the fob across its entire R35 generation from 2007 through 2024, making it one of the longest continuous fitments for any single FCC ID in the Nissan portfolio. The Altima (2007–2012), Maxima (2009–2014), and Murano (2009–2014) round out the Nissan applications.

For Infiniti, the device covers the EX crossover (2007–2013), the FX mid-size SUV (2009–2017), the G Line sedan and coupe family (2007–2015), and the Q60 (2014–2015). The Q60 fitment represents the tail end of a platform transition; the model was effectively a rebadged G37 coupe before Infiniti launched the fully redesigned Q60 on a newer architecture. Locksmiths working on these Infiniti models should note that while the FCC ID and transponder remain consistent, some year-to-year variations in body control module firmware may affect the specific programming sequence required.

PCF7952 Transponder and Programming Considerations

The PCF7952 is a combined RF transceiver and immobilizer transponder integrated into a single silicon package. It supports AES-based mutual authentication with the vehicle’s immobilizer ECU, which is a step above earlier unidirectional transponder protocols. For locksmiths, programming the KR55WK4 typically requires a diagnostic tool capable of communicating with the Nissan/Infiniti NATS (Nissan Anti-Theft System) module. Common professional platforms such as Autel IM608, Smart Pro, and similar advanced key programmers include Nissan NATS procedures that support the PCF7952 chip family.

The registration process generally involves connecting to the OBD-II port, reading the current key count and security status, and then initiating a learn procedure that pairs the new fob’s transponder ID with the vehicle’s NATS ECU. Some models may require a PIN code derived from the vehicle’s VIN through dealer or aftermarket security databases. The push-button start proximity detection function is typically learned simultaneously during the same OBD procedure, meaning the remote-start and passive entry features do not require a separate registration step.

When the fob’s CR2025 or CR2032 coin-cell battery (battery type varies by specific housing revision) drops below operating voltage, the passive entry and remote functions will stop working, but the PCF7952 transponder can still be read by the vehicle’s immobilizer antenna at close range. This is why holding a dead fob against the start button will still allow the engine to start — the transponder draws its power inductively from the antenna coil rather than from the internal battery.

NSN14 Emergency Blade Profile

The NSN14 is a high-security internal-cut (laser-cut) blade profile that has been standard across many Nissan and Infiniti vehicles since the mid-2000s. Unlike traditional edge-cut keys, the NSN14 features a serpentine track milled into the flat face of the blade, providing significantly more key differs and resistance to picking or bumping the mechanical lock cylinder. Aftermarket NSN14 blade blanks are widely available through locksmith supply channels, and cutting requires a machine with a high-security fixture — such as the Condor XC-Mini Plus, Triton Plus, or equivalent — configured for the Nissan internal-cut specification.

Because the KR55WK4 is a smart key, the emergency blade typically lives in a slot within the fob housing and is released by a small latch on the back of the unit. Vehicle owners should familiarize themselves with this release mechanism before an emergency arises, as locating the hidden blade slot under stress with a dead battery in a dark parking garage is not an ideal scenario.

When to Contact a Locksmith

Replacement of this smart key is not a do-it-yourself project. The PCF7952 transponder must be registered to the vehicle’s NATS security module, and the proximity detection system must be confirmed operational after programming. Automotive locksmiths with Nissan and Infiniti experience can typically complete the entire process — including blade cutting, transponder programming, and proximity function verification — in a single service call. Dealerships can also perform the work, though independent locksmiths often offer faster turnaround and lower cost for the same result.

For vehicles where all keys have been lost, the procedure becomes more involved and may require NATS PIN retrieval, EEPROM reading, or module replacement depending on the specific model year and security generation. Locksmiths should verify the exact NATS generation before quoting an all-keys-lost job on any of the covered fitments.

Related help: Nissan auto locksmith, Infiniti auto locksmith, car key replacement, car key programming.

Compatible and related keys: related key: Aftermarket Smart Key Fob, Infiniti OEM Smart Key Fob, Continental Automotive Smart Key Fob (FCC ID CWTWB1U), Lear Smart Key Fob (FCC ID CWTWBU624).