code p0171 leaking vacuum pump
P0171 - System too lean in bank 1
Meaning there is more air supply than fuel to the engine.This will fluctuate gas mileage. There will be hesitation in engine/acceleration.
1) Replace Upstream Oxygen sensor (Lambda sensor/Air-fuel ratio sensor) if no changes then check for vaccum leaks usually leaks from worn out hoses or loose gas cap
if that doesn't fix then its going to be hectic job next
2) Bad high pressure fuel pump
3) Intake manifold cleaning & gasket replacement
3) Bad fuel injectors (if black smoke coming out from tails)
Hope it helps!



