i have a 2000 nissan sentra gxe. it is a 5speen and has 101,000 miles on it. My idle has been acting uo ands the ses light is on. the code scanner is saying p0171 system to lean bank1 and p0174 system to lean bank2. i have seen posts on here talkin bout mafs and ecms and o2 sensors and i was wondering i can get some advice on how to check these sensors. and i was wondering if a vaccum leak could cause this problem.