Hi, if it is Linde 131 series, you should check speed sensor.
Discrepancy between channel A (1X1:9) and channel B (1X1:10) detected in speed sensor
Possible causes
Short-circuit between a phase U, V or W and the truck frame. The AC voltage on the frame must exceed 14V
Connection 1X2 is defective
Speed sensor is defective
Malfunction of the speed sensor is caused by a mechanical failure in the drive motor
BR,
Cleve