Nissan Repair Questions? Ask a Mechanic for Answers ASAP
Hello and welcome to just answer and allowing me to assist you. P0171 NISSAN - Fuel Injection System Too Lean Bank 1. Possible causes;
Intake air leaks- 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
- Engine Light ON (or Service Engine Soon Warning Light)- 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). You can easily check for air or vacuum leaks your self but the rest you would need a scanner to watch the oxy senor readings. Hope this gives you some options to go by and if you need further assistance I;ll be happy to do so.