Infiniti OEM Smart Key Fob – PCF7936 Chip, 315 MHz, NSN14 Blade
Sourcing decisions for the Infiniti OEM Smart Key Fob split between factory-original and aftermarket paths, with each route carrying trade-offs in cost, durability, and programming reliability. An OEM unit carries the advantage of validated circuit board tolerances and antenna tuning matched precisely to the vehicle’s receiver module; aftermarket variants of this fob may function identically but can introduce minor inconsistencies in signal strength or button tactile feel. The Infiniti OEM Smart Key Fob requires proper transponder registration to the vehicle’s immobilizer system regardless of sourcing channel. For technicians working on mid-2000s Infiniti models, every variant of the device must be verified against the target vehicle’s ECU before delivery to the customer. When replacing the Infiniti OEM Smart Key Fob, confirm the transponder type, operating frequency, and emergency blade profile match the original specifications.
Infiniti OEM Smart Key Fob: Technical Specifications
This smart key operates at 315 MHz, the standard frequency band used across most Infiniti vehicles sold in North America during this generation. The embedded transponder is a PCF7936, a widely recognized passive crypto transponder that communicates with the vehicle’s immobilizer ring antenna during ignition authorization. The PCF7936 handles the challenge-response authentication sequence that allows the engine control module to verify the key’s legitimacy before permitting engine start.
The integrated emergency key blade uses the NSN14 keyway profile. This mechanical blade allows physical door entry and, depending on model configuration, steering column ignition operation in the event of a dead fob battery or remote system failure. Locksmiths cutting an NSN14 blade should reference the original key or decode the door lock cylinder directly, as code pulling from the VIN may not always yield accurate bitting for this generation.
Vehicle Fitment: 2003–2008 Infiniti FX
The validated fitment for this fob covers the Infiniti FX produced from model years 2003 through 2008. The FX35 and FX45 variants within this range utilized the smart key system as part of Infiniti’s Intelligent Key platform, which integrated keyless entry, push-button start, and immobilizer authentication into a single handheld unit. Owners of these vehicles will recognize the fob as the primary interface for daily vehicle access and starting.
It is important to note that while the FX platform shared some electronic architecture with other Infiniti and Nissan models of the era, fitment should not be assumed across platforms without verification. The PCF7936 transponder and 315 MHz frequency were common in this period, but differing FCC registrations, button layouts, and case geometries can prevent cross-compatibility even when the core electronics appear similar.
Programming Considerations for Locksmiths
Registering this smart key to a 2003–2008 Infiniti FX requires a diagnostic tool capable of communicating with the vehicle’s BCM (Body Control Module) through the OBD-II port. The PCF7936 transponder must be written with the correct cryptographic seed value during the registration process. Most professional automotive locksmith platforms — including widely used tools from Advanced Diagnostics, Autel, and similar manufacturers — support this procedure for the FX platform.
The registration sequence typically involves placing the vehicle into a learning mode via the diagnostic interface, then presenting each fob to the system for enrollment. Up to a manufacturer-defined maximum number of keys can be registered at one time, and the process usually invalidates previously registered units unless they are re-enrolled during the same session. Technicians should advise the vehicle owner to have all functioning fobs present during programming to avoid unnecessary return visits.
Battery replacement within the fob is straightforward and uses a standard CR-series coin cell. However, replacing the battery does not affect transponder registration — the PCF7936 is a passive device powered by the immobilizer’s RF field, not by the fob’s internal battery. The battery powers only the remote keyless entry and push-button start proximity functions.
NSN14 Emergency Blade Details
The NSN14 keyway is a Nissan/Infiniti profile that appears across several model lines from this era. The blade is housed within the fob body and typically deploys via a small release lever or button on the key’s casing. For locksmiths, the NSN14 is a standard high-security profile that can be originated on most code machines equipped with Nissan/Infiniti jaw sets. Impressioning is also viable for this keyway, though code cutting from a known-good original is the preferred method for accuracy and efficiency.
When the fob’s battery is depleted or the remote electronics have failed, the driver can use this blade to unlock the driver’s door manually. Some FX models also allow emergency ignition start by holding the fob body against the steering column-mounted antenna ring, which powers the PCF7936 passively and permits the challenge-response cycle to complete without battery assistance.
OEM vs. Aftermarket Sourcing
Factory-original units for the 2003–2008 FX are available through Infiniti dealership parts departments, though pricing tends to be significantly higher than aftermarket alternatives. Aftermarket smart key shells — where the buyer transfers the original circuit board into a new casing — offer a cost-effective solution when the electronics remain functional but the housing is cracked or worn. Full aftermarket replacements that include both the case and a new PCF7936 transponder board are also produced, though technicians should verify the transponder’s compatibility and that the 315 MHz transmitter meets FCC emission standards before delivering the finished product to a customer.
Regardless of sourcing, the programming procedure remains the same. The vehicle’s BCM does not differentiate between an OEM and aftermarket transponder during enrollment — it only validates the cryptographic handshake. This makes aftermarket options a practical choice for budget-conscious vehicle owners, provided the locksmith verifies component quality before installation.
Specifications and fitment
| Key type | Smart Key |
|---|---|
| Transponder chip | PCF7936 |
| Frequency (MHz) | 315 |
| Keyway | NSN14 |
| Region(s) | USA |
| Product type | Smart Key |
| Compatible makes | Infiniti |
Listed vehicle fitment
| Make | Model | Years |
|---|---|---|
| Infiniti | FX | 2003–2008 |
Fitment must be confirmed against the existing key’s FCC ID family and the vehicle’s exact configuration before cutting or programming. VIN or photo verification may be required.
Questions and answers
Which vehicles does Infiniti OEM Smart Key Fob fit?
Infiniti OEM Smart Key Fob is listed to fit Infiniti applications such as Infiniti FX. Confirm the exact year range and the existing key’s FCC ID family before ordering, since fitment can vary by trim and region.
Does Infiniti OEM Smart Key Fob need programming?
Yes. Because it carries a transponder/remote function (chip PCF7936), it must be programmed (paired) to the vehicle’s immobilizer and, for remote functions, to the keyless-entry system. Many vehicles also require at least one working key to add a new one.
Does the blade need to be cut?
A push-to-start smart key has no traditional blade to cut in normal use, though many include an emergency insert key that can be cut separately.
Is Infiniti OEM Smart Key Fob OEM or aftermarket?
This listing is an aftermarket-grade replacement intended to match the original key’s electronic and mechanical specification. It is not required to carry a vehicle-brand logo and should be matched by FCC ID family and chip type rather than by appearance.
Check Fitment and Key Help
Low Rate Locksmith, a mobile automotive locksmith, can confirm whether Infiniti OEM Smart Key Fob matches an existing FCC ID family and coordinate cutting and programming when the vehicle configuration requires professional service. For dispatch and support, call (833) 439-8636 or email info@lowratelocksmith.com.
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