Hey grey535i,

I've been cutting and programming my own keys for years without problems so I might be able to assist.

Could you post a picture of the circuit board and transponder of the aftermarket key for me to look at?

My first thought is that the transponder you used might not be a genuine PCF7935. The replica transponders don't really work from my experience.

Those transponders will work with the EWS systems in E53s. They just won't store the mileage when the car is turned off like the 10030A transponders in the diamond keys.

The valet keys still use the PCF7935.

If you want a for sure working key I would purchase a used diamond key and remove the circuit board. Desolder the old 10030A chip and solder a new one in and program it to your EWS module with the AK90. Then place the circuit board in your new cut aftermarket key.

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