When attempting to drive my motorhome, I select the required gear, Reverse or Drive on the selector, the vehicle will move approximately two foot, then the gear trips into neutral. The first time this happened I had to get the van recovered to my local garage who diagnosed the following two fault codes from the ASM ECU:

U1900 CAN Communication Bus Fault
P0560 System Voltage Malfunction

The garage has investigated these faults and cannot find any problems, they cleared the fault codes from the ECU and the vehicle drove normally, however after standing for a couple of days, the problem recurred, this has now happened three times.

Is it possible that the ECU Codes can be updated and how could this be done. I'm loathe to spend mega ££££ at this stage. This problem has already cost me my holidays for this year.

Regards