Ford Smart Key Fob – ID49 Chip, 902 MHz | M3N-A3C054339

Fitments for the Ford Smart Key Fob span a wide cross-section of the Ford and Lincoln lineup, including the Bronco, Edge, Escape, Expedition, Explorer, F-Series, Fusion, Maverick, Mustang, Ranger, and Lincoln Aviator and Corsair — covering model years from 2016 through 2024. Across these platforms, the Ford Smart Key Fob handles passive entry and push-button start over a 902 MHz RF carrier paired with a low-frequency immobilizer transponder link. Each Ford Smart Key Fob communicates with the vehicle’s body control module during a cryptographic handshake authenticated by an NXP ID49 transponder chip embedded in the fob housing. Owners replacing the device should expect a programming procedure that typically requires professional diagnostic equipment, and when ordering a replacement, confirming the FCC ID M3N-A3C054339 ensures the correct unit is matched to the vehicle.

Ford Smart Key Fob Technical Specifications

The fob carries an NXP-manufactured ID49 transponder chip, which is part of NXP’s HITAG Pro family. ID49 uses AES-128 encryption for the immobilizer challenge-response sequence, representing a significant security upgrade over earlier Ford key & lock service transponder generations such as ID63 and 4D63. The 902 MHz operating frequency places this remote in the ISM band allocated for keyless entry systems in North America, distinct from the 315 MHz band used by many older Ford Remote Head Key – 4D63 Chip, HU101 Blade, 433 MHz key fobs and the 434 MHz band common in European markets.

The registered FCC ID for this unit is M3N-A3C054339. Locksmiths and parts departments can use this identifier to cross-reference OEM and aftermarket replacement inventories. Because multiple Ford Remote Head Key – 4D63 Transponder, HU101 Blade, 315 MH and Lincoln models share this FCC ID, it is important to verify the specific part number stamped on the back of the original fob or listed in the vehicle’s service manual before ordering.

Vehicle Fitment Details

The following validated fitments apply to the Ford Smart Key Fob bearing FCC ID M3N-A3C054339:

• Ford Bronco — 2021
• Ford Edge — 2017 through 2024
• Ford Escape — 2020
• Ford Expedition — 2018 through 2024
• Ford Explorer — 2016 through 2020
• Ford F-Series — 2017 through 2021
• Ford Fusion — 2017 through 2020
• Ford Maverick — 2022
• Ford Mustang — 2018 through 2023
• Ford Ranger (US) — 2019 through 2023
• Lincoln Aviator — 2020
• Lincoln Corsair — 2020

While this list covers confirmed applications, some model-year transitions introduced running changes mid-production. A 2020 Explorer built in December 2019, for instance, may carry different internal electronics than one assembled in August 2020. Verifying the FCC ID printed on the existing fob or scanning the vehicle’s PATS (Passive Anti-Theft System) module with a diagnostic tool eliminates guesswork.

Programming and Immobilizer Considerations

Programming the fob to a vehicle requires access to Ford’s PATS architecture. Late-model Ford vehicles equipped with ID49 transponder security generally demand an advanced diagnostic platform capable of writing new key credentials to the powertrain control module (PCM) and body control module (BCM). On-board programming shortcuts — such as the two-key add procedure available on older Ford models — are not supported on most vehicles that use this smart key.

Automotive locksmiths performing the programming procedure should confirm that the diagnostic tool’s software subscription covers the specific model year, since Ford periodically updates its security gateway protocols. The ID49 chip’s AES-128 encryption means that cloning from an existing fob is not a viable method; each unit must be individually registered to the vehicle’s immobilizer through the proper pairing sequence.

For vehicle owners, this translates to a process best handled by a qualified automotive locksmith or a Ford dealership service department. The specialized equipment and token-based authorization required for the ID49 immobilizer system go beyond what consumer-grade OBD-II scan tools can handle.

OEM Versus Aftermarket Replacement Options

OEM units sourced through Ford’s parts network guarantee factory-spec electronics and housing quality. Aftermarket alternatives carrying the same FCC ID M3N-A3C054339 are produced by several third-party manufacturers and can offer cost savings, though build quality — particularly of the internal circuit board shielding and battery contact springs — varies by supplier. Locksmiths who regularly program the Ford Smart Key Fob report that reputable aftermarket shells paired with OEM-grade ID49 transponder boards deliver reliable results at a lower price point than full OEM assemblies.

Regardless of the source, the replacement fob must contain a genuine NXP ID49 transponder and transmit on 902 MHz to be compatible with the vehicles listed above. Using a fob with the wrong transponder type or frequency will prevent both the keyless entry and the immobilizer authentication from completing successfully.

Battery and Maintenance

Smart key fobs of this type typically use a CR2450 or CR2032 coin cell battery, though the exact cell size depends on the physical shell variant. When the battery voltage drops below the operating threshold, the vehicle’s instrument cluster will display a key-battery-low warning. Even with a dead battery, the fob can still start the vehicle by holding it against the steering column-mounted backup reader, which powers the ID49 transponder inductively through the low-frequency immobilizer coil.

Periodic inspection of the fob’s rubber gasket and case seams helps prevent moisture ingress, which is the most common cause of intermittent smart key failures outside of battery depletion. A small flat-blade screwdriver or plastic pry tool is typically all that is needed to open the case for battery replacement without damaging the housing.