P0171 FUEL INJECTION SYSTEM FUNCTION — engine code Nissan Dualis, Qashqai HR16DE

DTC DETECTION LOGIC

With the Air/Fuel Mixture Ratio Self-Learning Control, the actual mixture ratio can be brought closely to thetheoretical mixture ratio based on the mixture ratio feedback signal from the heated oxygen sensors 1. TheECM calculates the necessary compensation to correct the offset between the actual and the theoreticalratios.In case the amount of the compensation value is extremely large (The actual mixture ratio is too lean.), theECM judges the condition as the fuel injection system malfunction and lights up the MI (2 trip detection logic).SensorInput signal to ECMECM functionActuatorHeated oxygen sensor 1Density of oxygen in exhaust gas(Mixture ratio feedback signal)Fuel injection controlFuel injector

DTC No:Trouble diagnosis nameDTC detecting conditionPossible cause
P0171Fuel injection system too
lean
• Fuel injection system does not operate properly.
• The amount of mixture ratio compensation is too
large. (The mixture ratio is too lean.)
• Intake air leaks
• Heated oxygen sensor 1
• Fuel injector
• Exhaust gas leaks
• Incorrect fuel pressure
• Lack of fuel
• Mass air flow sensor
• Incorrect PCV hose connection