CAN,Computer Area Network codes
 

I've got a ML320 from 1998 in my shop with a check engine light,we diagnosed that the Mass air flow sensor is faulty,we replaced the sensor and recommend a vehicle service , during the service we discovert heavily burned transmission fluid but the road test showed a good working /shifting transmission.We recommend to perform a transmission flush with filter exchange,what we performed after the customer authorized the additional work.
Now after delivering the ML 320 to the customer he complained that the transmission doesn't shift out of second gear after the engine is hot(ambient temp =85 degree.We checked codes again and found code 41/173CAN network fault.After reseting codes the ML drives fine as long you drive it,only when you turn off the engine and restart the transmission doesn't shift and the codes are back.I was checking with Alldata but couldn't find any conclusion. I NEED HELP.
Thank you