Question

2011 Subaru Forester with code P0171, can this be caused by using cheap gas?

Answer 1

Hi there,

This code is caused by a lean fuel mixture. The cheap gas won't cause this. This is usually caused by low fuel pressure, a bad mass air flow sensor or some type of vacuum leak after the mass air flow. This can also be caused by the front O2 sensor.

Answer 2

P0171 SUBARU Code - System Too Lean Bank 1

Read more: https://www.autocodes.com/p0171_subaru.html