Login  |  Register
Find local automotive repair shops in your area | AutoCodes.com Shops
Need A Repair Shop?
Find local automotive repair shops in your area.
CarZone Auto | Nissan and Infiniti Service Center

P0171 - 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
Tech notes
If the P0171 is combined with the P0174 code, it's very likely that the problem is caused by an intake leak. If there are no intake leaks, the next step is to replaced the air filter and clean the air flow meter. If the problem persist the front oxygen (O2) sensor may need to be replaced.
When is the code detected?
- Fuel injection system does not operate properly.
- The amount of mixture ratio compensation is too small. (The mixture ratio is too lean.)
Possible symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
- Excessive Fuel Consumption
P0171 Description

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 Malfunction Indicator Light (MIL) (2 trip detection logic).

P0171 Information for specific makes
P0171 ACURA Fuel Injection System Too Lean Bank 1
P0171 AUDI System Too Lean Bank 1  P0171 Video
P0171 BMW Mixture Control System Too Lean
P0171 BUICK Fuel Trim System Lean Bank 1  P0171 Video
P0171 CADILLAC Fuel Trim System Lean Bank 1
P0171 CHEVROLET Fuel Trim System Lean Bank 1  P0171 Video
P0171 CHRYSLER Fuel System 1/1 Lean
P0171 DODGE Fuel System 1/1 Lean
P0171 FORD Fuel Injection System Too Lean Bank 1  P0171 Video
P0171 GMC Fuel Trim System Lean Bank 1  P0171 Video
P0171 HONDA Fuel Injection System Too Lean Bank 1
P0171 HUMMER Fuel Trim System Lean Bank 1
P0171 HYUNDAI System Too Lean Bank 1
P0171 INFINITI Fuel Injection System Too Lean Bank 1
P0171 ISUZU Fuel Trim System Lean Bank 1
P0171 JAGUAR System Too Lean Bank 1
P0171 JEEP Fuel System 1/1 Lean
P0171 KIA Bank 1 System Too Lean
P0171 LAND-ROVER System Too Lean Bank 1
P0171 LEXUS Air/Fuel Mixture System Lean Bank 1
P0171 MAZDA Lean Air/Fuel Ratio Bank 1
P0171 MERCEDES-BENZ System Too Lean Bank 1
P0171 MITSUBISHI System Too Lean Cylinders 1-4
P0171 NISSAN Fuel Injection System Too Lean Bank 1
P0171 OLDSMOBILE Fuel Trim System Lean Bank 1
P0171 PONTIAC Fuel Trim System Lean Bank 1
P0171 SAAB System Too Lean Bank 1
P0171 SATURN Fuel Trim System Lean Bank 1
P0171 SCION Air/Fuel Mixture System Lean Bank 1
P0171 SUBARU System Too Lean Bank 1
P0171 SUZUKI System Too Lean Bank 1
P0171 TOYOTA Air/Fuel Mixture System Lean Bank 1
P0171 VOLKSWAGEN System Too Lean Bank 1  P0171 Video
Need more help?
Privacy Statement - Advertise with Us - Terms of Use - Copyright 1999-2016 Infinitihelp.com
AutoCodes.com - HelpForCars.net - Infinitihelp.com - Nissanhelp.com