What does P0171 code mean

The exhaust from the driver's side is too lean. A vacuum leak could introduce unmetered air the computer doesn't know about. An injector could be partially blocked with varnish. A misfiring cylinder will flow unburned fuel and air into the exhaust where only the unburned oxygen will be detected. A leak in the exhaust system could allow air to be drawn in before the oxygen sensor.

Chrysler is the only manufacturer that has been able to make an engine run right without a mass air flow sensor. For everyone else, any air that sneaks in that doesn't go through that sensor doesn't get included in the fuel needs calculation. That includes a leak in the fresh air tube between the mass air flow sensor and throttle body, a cracked or leaking vacuum hose, a leaking intake manifold gasket, or "a pcv hose that is torn to pieces". Replace that first, then see if the code comes back. I don't know if your Check Engine light will be off when you restart the engine, but if the problem isn't detected again, the code should self-erase after as many as 50 starts.