P0171 Lexus - Air/Fuel Mixture System Lean Bank 1
- 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
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.)
- Engine Light ON (or Service Engine Soon Warning Light)
- Excessive Fuel Consumption
P0171 Lexus 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).
LEXUS Technical Service Bulletins for P0171 code
2005 LEXUS RX330 Engine And Engine Cooling Details
2006 LEXUS RX330 Engine And Engine Cooling Details
2005 LEXUS RX330 060000 Engine And Engine Cooling Details
2006 LEXUS RX330 060000 Engine And Engine Cooling Details
2006 LEXUS LX470 Engine And Engine Cooling Details
2006 LEXUS RX400H Engine And Engine Cooling Details
2005 LEXUS ES330 Engine And Engine Cooling Details
2006 LEXUS ES330 Engine And Engine Cooling Details
2006 LEXUS GS300 Engine And Engine Cooling Details
2005 LEXUS GX470 Engine And Engine Cooling Details
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