How to Write and Reset a CGDI Keyless Go Key

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Matched product:

The CGDI MB FBS3 Keyless Go Key supports Mercedes-Benz 315/433MHz models, including:
W204 (C-Class), W207 (E-Class), W212 (E-Class), W221 (S-Class), W216 (CL-Class), W164 (ML-Class), W251 (R-Class), W166 (ML-Class), and W164 (GL-Class).

Guide: How to Write & Reset a CGDI Mercedes-Benz Keyless Go Key

Example vehicle: Benz W211

Preparation

1. Connect the CGDI MB Key Programmer to your computer via USB and supply power.
2. Place the CGDI MB Keyless Go key on the CGDI programmer coil.
3. Launch the CGDI MB software.

1. Writing a Benz Keyless Go Key

1). Navigate to EIS–EZS → OBD → Load File.

2). Select the original EIS data file containing the key information and password, then click Open.

• The EIS basic info and key password will load successfully.

3). Go to Read/Write Key → Read Key/Chip.

• The key version shows 76, meaning it's a "killer cookie."
• The key status should display Unused.

4). Click Open File / Write.

• Choose an unused 41-format file (e.g., key slot 4).

Note: Before writing, the key must be wiped by CGDI MB. If not wiped, writing will fail.



5). After writing succeeds, read the key/chip again.

• The key status will still show Unused, so it must be activated.

Activate the Key

• If possible, activate the key in the vehicle for best results.
• If activating in software:

1. Click Activate.
2. Copy the key password from EIS/EZS and paste it into the Read/Write Key page.
3. Ensure the key remains in the CGDI MB coil.

Note: Software activation may occasionally cause issues. If "Activate the KEY failed!" appears, click OK and try again. It will normally succeed on the second attempt.
Once activation succeeds, read the key/chip again.



The key status should now show Used.



2. Resetting a Benz Keyless Go Key
Method 1: Manual Reset

1). Remove the key from the CGDI MB programmer.

2). Press the trunk button, then press the lock button while holding the trunk button.

• The red LED will turn on.

3). Press the unlock button.

• The red LED will turn off — this indicates a successful reset.

4). Place the key back on the CGDI MB coil and read the key/chip.

• The key status should now be Unused.

5). Select the 41-format file again (e.g., key 4), write it, and activate.

• The key status will change to Used.

Method 2: Reset via CGDI MB Software

1). Click Reset.

2). The software will show Reset successful.



3). Read the key/chip again.

• The key status will change from Used to Unused.