– Faulty front heated oxygen sensor
– Ignition misfiring
– Faulty fuel injectors
– Exhaust gas leaks
– Incorrect fuel pressure
– Lack of fuel
– Faulty Mass Air Flow (MAF) sensor
– Incorrect Positive Crankcase Ventilation (PCV) hose connection
There is a factory service bulletin for the following Nissan models:
2004 Maxima (A34) with 5 speed A/T only
2004 Quest (V42) with 5 speed A/T only
Nissan Factory Service Bulletin OBDII Code P0171
2004 Maxima (A34) with 4-speed A/T and 6-speed M/T
2004 Quest (V42) with 4-speed A/T
Nissan Factory Service Bulletin OBDII Code P0171
– The amount of mixture ratio compensation is too small. (The mixture ratio is too lean.)
– Excessive Fuel Consumption
With the Air/Fuel Mixture Ratio Self-Learning Control, the actual mixture ratio can be brought closely to the theoretical mixture ratio based on the mixture ratio feedback signal from the heated oxygen sensors 1. The Engine Control Module (ECM) calculates the necessary compensation to correct the offset between the actual and the theoretical ratios.
In case the amount of the compensation value is extremely large (The actual mixture ratio is too lean.), the ECM judges the condition as the fuel injection system malfunction and light up the MIL (2 trip detection logic).