Here’s the solution for Xhorse VVDI2 prepares Audi A6/Q7/Allroad 4th immobilizer dealer key successfully but fail to star car.
Reason: The step for key learning is skipped/wrong.
please check guides below to to learn the key correctly.
Audi 4th Immobilizer system- Audi A6/Q7/Allroad
This type use MEGAMOS 8E transponder
If you want prepare a new dealer key, you must know the total 12 bytes CS.
But there’s only 6 bytes CS in ECU, so we need read the whole J518 EEPROM dump.
Read CS from ECU, only read 6 bytes CS and PIN. With 6 bytes CS and PIN help, VVDI2 can use OBD standard method to read/write EZS-Kessy EEPROM (J518), read/write VIN etc
Step 1: Autodetect from engine ECU
Step 2: Read and save EZS-Kessy EEPROM (J518)
Step 3: Load J518 eeprom dump file
Step 4: Make dealer key
Step 5: Key Learning
Note: OBD standard method only support 9S12DT128 type.
In J518 use 9S12DT128 chip (most cars before 2009 use this type).
But does not support J518 with 9S12DT(G)256 chip (most cars after 2009 use this type.)
That means 9S12DT(G)256 type doesn’t support prepare a dealer key with this method.
VVDI2 also can read J518 dump as service model what is only used for make normal dealer key, need to make sure which is chip model, VVDI will read wrong data if is no match, so first make sure what chip it is.
Read dump with working key is only can be used for make normal dealer key, not for OEM key, neither for write back to KESSY.