Hyundai Smart Key Fob (FCC ID SY5HMFNA04) – PCF7952A 433 MHz Key

Operating at 433 MHz with an NXP PCF7952A transponder, the Hyundai/KIA OEM 4-Button Smart Key Fob – NCF2951X Genesis Fi Smart Key Fob (FCC ID SY5HMFNA04) provides both passive keyless entry and push-button start functionality across a broad range of Hyundai vehicles. This unit carries the KK10 blade profile for its integrated emergency key insert, a detail that matters when mechanical access is needed during battery failure or signal interference. Inside the fob sits the PCF7952A — a combined RFID transponder and microcontroller responsible for immobilizer authentication and rolling-code remote communication. Compatible vehicles span sedans, crossovers, and coupes produced between 2006 and 2018, all sharing the same 433 MHz receiver architecture. A correctly enrolled Hyundai Smart Key Fob (FCC ID SY5HMFNA04) will allow proximity-based unlocking, engine start authorization, and remote trunk release without removing the device from a pocket or bag. The Hyundai Smart Key Fob (FCC ID SY5HMFNA04) remains one of the most widely cross-referenced smart key SKUs in the Hyundai aftermarket parts ecosystem.

Technical Specifications of the Hyundai Smart Key Fob (FCC ID SY5HMFNA04)

The FCC registration under ID SY5HMFNA04 confirms the fob’s 433 MHz operating frequency, which is the standard band used across international-market Hyundai key & lock service models and many USDM variants from the late 2000s through the mid-2010s. This frequency separates it from certain North American–specific Hyundai smart keys that operate at 315 MHz — a distinction locksmiths must verify before ordering replacement hardware.

At the heart of the device is the NXP PCF7952A, a multi-function chip that combines a passive HITAG2-compatible transponder with an active microcontroller capable of generating encrypted rolling codes. The passive transponder element handles immobilizer challenge-response authentication when the fob is held near the dashboard start button or emergency key cylinder. The active microcontroller manages all RF communication — lock, unlock, panic, and trunk release signals — transmitted at 433 MHz. This dual-function architecture within a single IC is what enables true smart key operation, as opposed to older systems that used separate transponder chips and remote modules.

The emergency key blade is cut to the KK10 keyway, a profile associated with Hyundai’s mechanical lock cylinders from this generation of vehicles. When a fob battery dies or the passive entry system experiences interference, the physical blade can be extracted from the fob housing and used to manually unlock the driver door. Locksmiths cutting replacements should note that KK10 blanks are distinct from the HY18 and HY20 profiles used on other Hyundai model years, and cross-referencing to the correct blank is essential for a functional mechanical key.

Vehicle Fitment Guide

This smart key covers a wide range of Hyundai models spanning over a decade of production. The validated fitments include:

• Hyundai Accent — 2010 through 2017 model years
• Hyundai Azera / Grandeur — 2012 through 2017
• Hyundai Elantra — 2010 through 2016
• Hyundai Equus — 2010 through 2013
• Hyundai Genesis — 2009 through 2013
• Hyundai i30 — 2007 through 2012 (first generation) and 2012 through 2017 (second generation)
• Hyundai i45 — 2009 through 2014
• Hyundai IX35 — 2010 through 2017
• Hyundai Santa Fe — 2006 through 2012
• Hyundai Sonata — 2009 through 2014
• Hyundai Tucson — 2009 through 2015
• Hyundai Veloster — 2011 through 2018
• Hyundai Verna — 2012 through 2017

Several of these models — notably the i30, i45, IX35, and Verna — are primarily sold outside the US market, which explains the 433 MHz frequency selection over the 315 MHz band more common in USDM Hyundai vehicles. Locksmiths working with import or grey-market vehicles in North America should be aware that the receiver module in these cars expects 433 MHz communication, and a 315 MHz aftermarket fob will not function regardless of correct programming.

Programming Considerations for Locksmiths

Enrolling this smart key into a Hyundai immobilizer system requires a diagnostic tool capable of communicating with the vehicle’s smartkey ECU — sometimes referred to as the SMK (Smart Key Module) or the BCM (Body Control Module), depending on the model year and market. Tools from major diagnostic platforms such as Autel, Xtool, and the Hyundai GDS platform support PIN-code-based programming for most vehicles in the fitment list above.

The PCF7952A chip inside the fob must be initialized and paired to the vehicle’s specific immobilizer seed. Unlike simpler transponder cloning procedures, smart key enrollment involves writing encrypted data to both the chip and the vehicle’s ECU, establishing a unique cryptographic handshake. This means a blank replacement fob cannot simply be cloned from an existing key — it must go through the full on-board programming or EEPROM-level procedure.

For vehicles where the PIN code is not available through standard diagnostic retrieval, locksmiths may need to read the immobilizer data directly from the smartkey ECU EEPROM. The specific EEPROM location and data format vary by model. On the Sonata and Elantra platforms from this era, the SMK unit is typically accessible behind the dashboard, while on the Santa Fe and Tucson, it may be located near the steering column.

After successful enrollment, the fob should be tested for all functions: passive entry detection at each door handle, push-button engine start, remote lock and unlock, and trunk release. A failure in any one of these functions while others work correctly often indicates an antenna issue in the vehicle rather than a fob defect.

KK10 Emergency Blade Details

The KK10 blade profile integrated into this fob serves a backup role only — it unlocks the driver door mechanically but does not bypass the immobilizer. Owners who find themselves with a dead fob battery can extract the blade from the fob housing (typically by pressing a small release tab on the back), unlock the door, and then hold the fob body against the start button to allow the passive transponder to communicate via inductive coupling. This near-field communication draws power from the vehicle’s antenna ring rather than the fob battery, enabling a start even with a completely depleted CR2032 or equivalent cell.

Locksmiths should stock KK10 blanks separately from the fob when handling mechanical key duplication requests. The blade is not interchangeable with HY18 or TOY48 profiles despite superficial visual similarity. Cutting data for KK10 is available through standard code-cutting software from Ilco, JET, and similar platforms.

OEM vs. Aftermarket Sourcing

The SY5HMFNA04 is available from both OEM Hyundai parts channels and aftermarket smart key suppliers. OEM units arrive pre-loaded with the correct PCF7952A transponder and are ready for on-board programming. Aftermarket alternatives vary in quality — the critical factor is confirming the presence of a genuine NXP PCF7952A chip rather than a clone IC, as counterfeit chips may fail during the cryptographic enrollment phase or exhibit unreliable RF performance at 433 MHz.

When sourcing aftermarket units, verifying the FCC ID printed on the device or its packaging against SY5HMFNA04 provides a baseline confirmation. However, the FCC ID alone does not guarantee internal component authenticity. Opening the fob housing and visually inspecting the PCF7952A IC markings is the most reliable method for locksmiths who process high volumes of Hyundai smart key replacements.

When to Contact a Professional Locksmith

Vehicle owners dealing with a non-functional or missing smart key for any of the models listed above should engage a qualified automotive locksmith rather than attempting self-programming. The cryptographic enrollment process for the PCF7952A-based system is not accessible through owner-level procedures — there is no “insert key, turn ignition three times” shortcut for smart key systems of this generation. Professional locksmiths equipped with the appropriate diagnostic hardware can typically complete a full replacement and programming on-site, including emergency blade cutting to the KK10 profile, in under an hour.