P0171 Nissan - where should I begin looking for problem?

Question

my Nissan Sentra is showing an engine code po171, and I am trying to locate the problem. can you give me any guidance or information on where to start and where to look? thank you!

Answer 1

Hi there,

Start by looking for intake manifold leaks. If there aren't any vacuum leaks, then the mass air flow sensor outputs should be checked. The maf sensor is the most common issue. If the maf checks out good, then the next step should be looking at the outputs from the O2 sensors. Of course, you need a scan tool to check these items.