ML320 2002 transmission problem P2203
 

Hi gents,
I have ML 320 (2002), auto transmission, 60 k miles.
Had a problem. Transmission went into malfunction (without any lights indications on the panel). Malfunction means that i could drive only in 1st gear. I went to the service, they checked alarm messages. There were 2 messages: 1 engine, 1 transmission. I just remember number of alarm: P2066 (engine) and P2203 (transmission). They deleted alarms from memory and problem was solved.
My question is what was the cause of problem? Would it appear in future? Because i didn't change any part of car for solving of problem i'am afraid that i don't know when and where it will/could be happened again :-((
Any suggestions?
Thanks in advance,
Patamdar