I noticed some loud rattling grinding sound when i got in my car on the way home from work today. thought it might be something bad, it would happen when i put my car in reverse or start to drive or turn the wheel. i stuck my head under and had my girlfriend mess around with the wheels and pop it in and out of drive and i saw the exhaust pipes were shaking in the middle of the car.... turns out it was a broken clamp, the bolt rotted thru so i ordered new upper lower and bolt. But, my ses light also came on while i was driving like this. PO174 is the code i get on a generic odb2. it says system is to lean (bank 2 ). i got this code before 2 months ago i cleand the mafs and turned the ses light off and it stayed untill now. Does anyone know why this code comes up. Could i have a crack in my exhaust or maybe just a dirty sensor or what. i dont know im stumped . i figured it could also be a vac leak but i havnt found one yet. any help thoughts would be great, thanks !