FAQ Keydiy KD-X4 2018- JLR Smart Key Copy Function

Recently, customers have had many questions regarding the 2018+ Jaguar & Land Rover smart key copying function of Keydiy KD-X4 & ZB24-5 JLR remote. Here, we would like to address some of the most frequently asked questions for our customers.

Question 1: Will the new key stop working after 256 clicks like the others?

 

Answer:

There will be no sync issue. you copy to ZB key all of the orginial key data, but you change ID of ZB key to original lost key’s ID. So, after programming, there will be no crossover of keys, cause there will be 2 different keys (original and ZB key) with 2 different key ID’s.

The key will work no matter you click hundreds of times.

 

Question 2: Does this clone peps “UWB” and PS fob types?  What about PEPS, does it work? Is it necessary to disable the USB (UWB) function before copying?

 

Answer:

It depends on the key.

If you are using a ZB smart remote, an aftermarket key, or a original factory key without UWB, you must disable the UWB function.

If you are using an original factory high-config key, then you do not need to disable UWB.

Important note: Even if you use an original factory high-config key and complete the matching process, it only means the original factory UWB function remains unaffected. The new key’s UWB will still not function directly. Therefore, if the vehicle owner requires the new key to have full UWB functionality, you will still need to replace the KVM chip and perform regular key programming.

 

 

Question 3: If I overwrite the original key ID position, will the original key remote control still work?

Answer:

No. If you overwrite the original key ID position, once the new key’s remote is used, the original key’s remote function will be lost.

Important note:

When using the NXP29 cloning function only, the newly cloned key will work, but the original key’s remote function can still be restored within a short period of time.

However, if you use the OBD copy (programming) method, the original key’s function will be permanently lost.

 

Question 4: Why did you connect device to car? 

Answer: After connecting KD-X4 to car, the device will detect if the car has UWB function and disable it.  If the UWB is enabled unless you disabled it before you can copy.

 

Question 5: How about 3rd key? Can I copy one more smart key like this?

Answer: No, you can only copy 1 spare key using the feature. If need to add 3rd smart key, still need to replace KVM chip to add key.

First, verify how many working keys the owner currently has. If there are already two functional keys and the owner wants to add an additional one, you will most likely need to replace the KVM chip and proceed with the normal smart key programming steps.

 

Question 6: If I use the Land Rover 2018+ key copying function and occupy a lost key position, what is the procedure to restore the lost key’s function if it is later found?

Answer:

First option: Perform the copy process again — read the data from the new key and write it back into the recovered (previously lost) key.

If UWB does not work after writing back, you will need to replace the KVM (Keyless Vehicle Module) chip, then use the “Add” option to re-match the key. This will restore the original lost key’s remote functionality.

Note: For UWB-equipped high-trim models, on some vehicles, you will also need to go into the vehicle’s infotainment/system settings and reconfigure the UWB settings after programming.

 

 

Question 7: What about writing to an original key with UWB?

Answer: If you need to add an original key with UWB, replace KVM chip to add a spare key instead of copying key.

 

Keep updating…

 

NXP PCF7939MA vs PCF7939FA Chip

Why do so many technicians buy a PCF7939 thinking they are all the same… only to discover their mistake when they already have the key in hand?

At first glance, they look like almost the same transponder.

Both belong to the NXP PCF7939 transponder family.

Both use modern technology.

And both appear constantly in catalogs.

But that is where the resemblance ends.

What if, before buying a key, you could identify in seconds whether you need a PCF7939MA or a PCF7939FA?

Let’s learn to distinguish the differences between them.

Feature	PCF7939MA	PCF7939FA
Most Common Commercial ID	ID4A	ID49
Technical Family	HITAG AES	HITAG PRO
Security	AES 128 BITS	AES 128 BITS
Frequent Applications	RENAULT, DACIA, NISSAN, KIA, HYUNDAI, PEUGEOT	MODERN FORD AND OTHER SPECIFIC PLATFORMS
Direct Equivalence	NO	NO
Substitution Between Both	SHOULD NOT BE ASSUMED	SHOULD NOT BE ASSUMED

Dimension	The Wrong Path	The Correct Path
Core Action	Assuming they are the same / Blind substitution	Verifying information / Confirming model
Time Cost	Loss of time: Repeated diagnostics, unnecessary tests	Save time: Identify the correct chip from the first attempt, faster jobs
Money Cost	Loss of money: Rejected jobs, dissatisfied clients	Save money: Less rework, higher client satisfaction
Technical Result	Failed programming: The incorrect chip can block the process	Successful programming: Use the appropriate chip and avoid lockouts
Professional Impact	Damage to reputation: Improvisation is not professional	Generate trust: Professionalism strengthens your reputation

 

The suffix matters too
Many people read only:
PCF7939
And stop reading there.
But the last two letters completely change the identification.
PCF7939MA
Does not mean the same thing as
PCF7939FA
That small detail can determine whether or not the key is the right one for the vehicle.
Action plan
• Step 1: Read the full part number.
• Step 2: Do not leave out the final letters.
• Step 3: Confirm the variant before buying.

Now, let’s look at the difference that appears most frequently in catalogs.

 

ID4A is not the same as ID49.
You will generally find this relationship:
PCF7939MA → ID4A
PCF7939FA → ID49
That information alone helps avoid many selection errors.
Although both belong to the PCF7939 family, they serve different applications.
Action plan
• Step 1: Identify the commercial ID.
• Step 2: Match it to the physical part number.
• Step 3: Do not interchange them just because they share the same prefix.

There is yet another important difference.

 

Technology evolves, too.
The PCF7939MA is typically associated with:
HITAG AES.
Whereas the PCF7939FA is normally linked to:
HITAG PRO.
Both utilize 128-bit AES-based security.
However, that does not mean they are interchangeable.
Action plan
• Step 1: Check the specified technology.
• Step 2: Verify the transponder part number.
• Step 3: Do not confuse security with compatibility.

Now, let’s look at where each one is typically found.

 

The applications also differ.
Various commercial catalogs typically link the:
PCF7939MA (ID4A) to vehicles such as:
Nissan.
Renault.
Dacia.
Kia.
Hyundai.
Peugeot.
Whereas the PCF7939FA (ID49) is commonly found in:
Modern Ford models.
And other specific platforms.
Always confirm the exact application based on the vehicle.
Action plan
• Step 1: Identify the vehicle.
• Step 2: Consult a reliable catalog.
• Step 3: Verify the part number before ordering the key.

But there is still one detail that causes a lot of confusion.

 

 

Same manufacturer… different application
NXP developed the PCF7939 family.
However, the specific variants are distinct products.
That is why much of the available information comes from key manufacturers, diagnostic equipment providers, and specialized catalogs.
The conclusion is simple:
Sharing a family does not mean sharing compatibility.
Action plan
• Step 1: Consult more than one source.
• Step 2: Cross-reference the information with the vehicle.
• Step 3: Avoid assuming equivalencies.

All that remains is the lesson that helps beginners the most.

 

The applications also differ.
Various commercial catalogs typically link the:
PCF7939MA (ID4A) to vehicles such as:
Nissan.
Renault.
Dacia.
Kia.
Hyundai.
Peugeot.
Whereas the PCF7939FA (ID49) is commonly found in:
Modern Ford models.
And other specific platforms.
Always confirm the exact application based on the vehicle.
Action plan
• Step 1: Identify the vehicle.
• Step 2: Consult a reliable catalog.
• Step 3: Verify the part number before ordering the key.

But there is still one detail that causes a lot of confusion.

 

Technicians who rarely buy the wrong parts do this:
They don’t memorize thousands of models.
They memorize four key details:
Physical part number.
Commercial ID.
Technology.
Application.
With that information, they can correctly identify most modern transponders without relying solely on photographs.
That habit minimizes errors right from the start.
Action plan
• Step 1: Learn the full part number.
• Step 2: Link it to its commercial ID.
• Step 3: Always confirm the application before buying or programming.

Properly identifying the transponder usually saves far more time than trying to fix a mistake after buying the wrong part.

Top 6 Tips to Copy 2018+ Smart Key using Keydiy KD-X4

Keydiy KD-X4 2018+ Jaguar & Land Rover smart key function is ready now.

Advantages:
1: No KVM Module disassembly required
2: No online programming needed
3: Secure with no code tracking
Compatible with both original factory keys and KD ZB smart keys. Simpler, safer, faster!

Here are the top 6 tips to add/copy 2018+ JLR Smart Key using KD-X4:

1. Mandatory Pre-Operation Step:
Before starting, read the IDs of both original keys inside the vehicle. This is a critical core step and must not be skipped, as it directly affects the validity of subsequent key matching.

 

2. Original Key Chip Read Requirements:
Original keys come in two chip types: A4 and AF. Reading methods are clearly distinguished:

• A4 chip: Supports two reading modes – chip removal reading and soldered wire reading.
• AF chip: Can ONLY be read by removing the chip and using the dedicated #13 NCF29xx adapter board. No other reading methods are available.

 

3. Key Generation & Programming Rules:
When generating a new key, you must select the ID corresponding to the lost original key. If the original key to be read is damaged, you may force-modify it to the same ID for adaptation. Once this operation is performed, the old original key will be permanently invalidated and can no longer be used.

 

4. Programming Original Key – Strict Requirement:
When using an original key for generation and matching, the new key MUST have the exact same chip model and transmission frequency as the original vehicle key. Mixed or mismatched pairing is strictly prohibited.

 

5. High/Low Config Key Restrictions:
Original keys are available in UWB and Non-UWB versions. High‑config keys are equipped with UWB (Ultra-Wideband) functionality. For AF-chip high‑config models, ONLY original UWB keys can be copied – standard aftermarket remotes are NOT compatible.

If the vehicle is equipped with UWB functionality and the original key has UWB capability, you MUST use an original high‑config key. Low‑config keys are NOT compatible.

 

6. Practical Preparation Recommendation:
It is strongly recommended to have the KD ZB24 remote in stock before starting the procedure to ensure a smooth and successful matching process.

 

Take the 2020 Range Rover as an example:

Connect KD-X4 device with vehicle via OBD.

Run KD App.

Go to IMMO Programming-Land rover (2018-2021)- Copy the key- 2018+ disassemble key to copy.
Select Copy key programming.
KD-X4 will detect if the vehicle has UWB function and read VIN.
Check key wiring diagram.

Disassemble original key.

Solder KD DB25 adapter wires to the keyboard.

Then connect DB25 adapter with KD-X4.

Read and save data.

Disconnect the original key board.

Place a KD ZB24 smart remote to the KD-X4’s coil. If you are copying a KD remote, do not remove its shell.

Select key ID.
Choose write into KD remote.
Choose correct frequency.
Write chip data to the new KD key.

Don’t need to be programmed afterwards.

Test both keys.