Hello John, thank you very much for your answer. I will check it out.
Best regards

ok, sorry bout the confusion on the serial number, i must have looked at it wrong, i rechecked it and it is good :o)

first make sure you battery is fully charged before testing

now... for the codes
code 51 is an accelerator sensor fault
check the accelerator and make sure it is returning completely back to neutral. Either trash or the floorpad can get under the heel of the pedal and not allow it to return all the way back.
Once you rule out this and it still gives code then the sensor itself may be bad or just out of adjustment and needs to be reset/re-calibrated.

as for code 30
this indicates an armature fault P
P being the pump circuit
check all your wiring and power cables to the pump motor and check the brushes in the motor.

Hello John. Thank for your fast reply. There are not any other symbols displayed on the dash.I have error codes 51 and 30 and the serial is corect ETB4A00374.
Best regards

are there any other symbols illuminated besides the !?
are there any number codes being displayed on the dash display?
also the serial number you provided is incorrect
would it happen to be ETB4B00374? please double check this first