Lear Smart Key Fob (FCC ID CWTWBU735) – ID46 315 MHz Nissan Key
Used across the Nissan Maxima and Nissan Sentra platforms, the Lear Smart Key Fob (FCC ID CWTWBU735) serves as the factory-issued proximity key for passive entry and push-button start. Each Lear Smart Key Fob (FCC ID CWTWBU735) integrates an ID46 transponder chip paired with a 315 MHz RF communication link, enabling both immobilizer authentication and remote keyless functions through a single unit. For technicians working on Nissan’s Intelligent Key system, this fob requires careful attention during enrollment because of how the BCM validates both the transponder seed and the RF rolling code simultaneously. Owners who need a replacement can expect the device to perform identically to the original once properly registered to the vehicle. A correctly programmed Lear Smart Key Fob (FCC ID CWTWBU735) will restore full smart-key functionality — door proximity unlock, trunk release, and engine authorization — without any degradation from the OEM experience.
Lear Smart Key Fob (FCC ID CWTWBU735) Technical Specifications
The core of this smart key is its ID46 transponder, a widely adopted crypto chip used across many Nissan models from this era. The ID46 handles the cryptographic handshake between the fob and the vehicle’s immobilizer module. When the driver carries the device near the door handle or places it inside the cabin, the car’s antenna coil energizes the transponder and initiates an encrypted challenge-response sequence. Only after the immobilizer confirms a valid response does the vehicle permit engine cranking.
On the RF side, the fob operates at 315 MHz, the standard frequency for North American market Nissan proximity keys. This frequency is used for the remote lock/unlock commands as well as the passive polling that detects the key’s presence near the vehicle. The FCC ID CWTWBU735 is registered under Lear Corporation, which manufactured this smart key unit for Nissan’s OEM supply chain.
Vehicle Compatibility
Based on validated fitment data, this smart key covers the following Nissan models and model years:
- Nissan Maxima: 2007–2008
- Nissan Sentra: 2007–2012
The 2007–2008 Maxima used Nissan’s Intelligent Key system as standard or optional equipment depending on trim level. These sixth-generation Maxima models rely on the BCM to manage proximity detection zones — typically one antenna per door handle and one or more inside the cabin. The fob must be recognized by the system before the push-button ignition will function.
The 2007–2012 Sentra spans a broader production window, encompassing the B16 generation. Certain Sentra trim packages equipped with Intelligent Key utilized this same Lear-manufactured unit. Because the Sentra was produced in higher volumes than the Maxima during this overlap period, this particular FCC ID sees steady demand in the aftermarket replacement channel.
Programming and Registration Procedure
Registering the fob to a Nissan vehicle equipped with Intelligent Key typically requires a diagnostic scan tool capable of communicating with the BCM over CAN bus. The standard procedure involves entering a key registration mode, placing the new smart key inside the vehicle (usually on the designated spot on the instrument panel or center console), and instructing the BCM to learn the unit’s transponder ID and RF serial number.
Nissan’s system generally supports up to four registered intelligent keys per vehicle. During programming, all existing keys should be present so the BCM can re-register them alongside the new one. If only the new fob is presented, previously registered keys may be erased from memory — a consideration that automotive locksmiths routinely manage during service calls.
The ID46 transponder in this device uses a crypto algorithm that requires the programmer to generate a valid seed/key pair. Professional-grade tools from major diagnostic manufacturers support this process for the covered Nissan models. Attempting registration with consumer-grade OBD tools that lack immobilizer functionality will not complete the transponder pairing, even if the RF portion appears to sync.
OEM vs. Aftermarket Considerations
Because Lear Corporation produced this unit under Nissan’s OEM contract, the original fob carries the CWTWBU735 FCC ID and meets all factory specifications for RF output power, antenna tuning, and transponder response timing. Aftermarket alternatives bearing the same FCC ID are available in the replacement parts market and function identically when sourced from reputable suppliers.
When evaluating a replacement, locksmiths and vehicle owners should verify the FCC ID printed on the back of the unit matches CWTWBU735. Visually similar Nissan smart keys with different FCC IDs — such as those from later model years or different vehicle platforms — may not be compatible with the 2007–2012 Sentra or 2007–2008 Maxima BCM firmware, even if they physically resemble this fob.
Emergency Start and Low-Battery Operation
If the internal battery of the fob is depleted, the Nissan Intelligent Key system provides a backup start method. The driver places the device directly against the push-button start switch, which has an integrated short-range antenna. This close-proximity contact allows the immobilizer to power the ID46 transponder inductively — the same way a traditional transponder key works — bypassing the need for the 315 MHz RF link. The engine will start, though remote lock and unlock functions will remain inoperative until the battery is replaced.
Battery replacement in this smart key is straightforward. The housing separates along a seam, typically accessible with a small flathead screwdriver or coin. The internal CR2032 or CR2025 cell (depending on the specific housing revision) should be replaced with a fresh unit, taking care not to touch the circuit board contacts. No reprogramming is necessary after a battery swap — the transponder ID and RF codes are stored in non-volatile memory.
When to Contact a Locksmith
Professional locksmith service is the most practical route for programming this smart key outside of a Nissan dealership. Mobile automotive locksmiths equipped with advanced diagnostic tools can perform the full registration — both RF and transponder — at the vehicle’s location. This is particularly relevant for the Nissan Sentra owners in the 2007–2012 range, where dealership proximity may be inconvenient and the vehicle’s age makes dealer service less cost-effective compared to independent locksmith rates.
Situations that specifically call for professional intervention include total key loss (where no registered fob is available to initiate the standard add-key procedure), non-responsive push-button start despite a fresh battery, and cases where a used replacement fob needs its previous vehicle registration cleared before it can be paired to a new car.
Specifications and fitment
| Key type | Smart Key |
|---|---|
| Transponder chip | ID46 |
| Frequency (MHz) | 315 |
| FCC ID(s) | CWTWBU735 |
| Region(s) | USA |
| Product type | Smart Key |
| Compatible makes | Nissan |
Listed vehicle fitment
| Make | Model | Years |
|---|---|---|
| Nissan | Maxima | 2007–2008 |
| Nissan | Sentra | 2007–2012 |
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 Lear Smart Key Fob (FCC ID CWTWBU735) fit?
Lear Smart Key Fob (FCC ID CWTWBU735) is listed to fit Nissan applications such as Nissan Maxima, Nissan Sentra. Confirm the exact year range and the existing key’s FCC ID family before ordering, since fitment can vary by trim and region.
Does Lear Smart Key Fob (FCC ID CWTWBU735) need programming?
Yes. Because it carries a transponder/remote function (chip ID46), 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 Lear Smart Key Fob (FCC ID CWTWBU735) 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 Lear Smart Key Fob (FCC ID CWTWBU735) 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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