I have a 2004 bmw 525i . it has automatic trasmission. it stopped shifting gear after second gear . a mechanic said changing the transmission oil might fix the problem. after oil change it was able to change gear but would slip from second to 3rd gear. after a while same problem started again and it gave the warning "transmission fault". I took it to carmax to see if they would buy it for a reasonable price. On their evaluation report it said that transmission is ok and engine is running improperly. right now my car doesnt shift gear from first gear and transmission fault light is on all the time. I am confused about the diagnosis. can it be from Solenoids. can you please tell me the possibilities and what you think the cost for fixing it should be? I appreciate your response.