well i was going on a trip to weyburn from regina about a 1-1.5hr trip then when i get to weyburn i noticed that my truck was starting to smell inside like burnt oil. so i got to my dads shop and parked it inside and then i noticed there was oil dripping from everywhere it was all over the skid plates and everything. so i put it over the pit and noticed it was coming from the diffriental. so then i added oil to it and then pulled it out of the shop. as im going i hit some deep snow and needed 4x4 to get through it. i put it in 4hi and start driving as im goin the brake light comes on i get through the snow and stop then it goes away. so i checked the code on my trip thing and it said P2161 i believe ill have to double check. could anyone please tell me what this means.