AutoCodes - Toyota - P0171 TOYOTA

P0171 TOYOTA Code - Air/Fuel Mixture System Lean Bank 1

Repair Importance Level: 3/3
Repair Difficulty Level: 3/3
What does this mean?
Table of contents
What does this mean?

|P0171 TOYOTA code 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

|How do I fix the P0171 TOYOTA code?

Check the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.
What does this mean?

|P0171 TOYOTA code 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 replace the air filter and clean the airflow meter. If the problem persists the front oxygen (O2) sensor may need to be replaced.

There is a factory service bulletin for the following Toyota models:
2005–2007 Toyota Avalon
2007–2008 Toyota Camry
2005-2007 Toyota Avalon, 2007-2008 Toyota Camry Factory Service Bulletin OBDII Code P0171

2005-2006 Toyota Corolla
2005-2006 Toyota Matrix
2005-2006 Toyota Corolla, Matrix Factory Service Bulletin OBDII Code P0171













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|Cost of diagnosing the P0171 TOYOTA code

Labor: 1.0

The cost of diagnosing the P0171 TOYOTA code is 1.0 hour of labor. The auto repair's diagnosis time and labor rates vary by location, vehicle's make and model, and even your engine type. Most auto repair shops charge between $75 and $150 per hour.

|When is the P0171 TOYOTA code detected?

- Fuel injection system does not operate properly.
- The amount of mixture ratio compensation is too small. (The mixture ratio is too lean.)

|What are P0171 TOYOTA code possible symptoms?

  • Engine Light ON (or Service Engine Soon Warning Light)
  • Excessive Fuel Consumption

|P0171 TOYOTA code 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 MIL (2 trip detection logic).
OBDII Code P0171 Toyota - Air/Fuel Mixture System Lean Bank 1 - AutoCodes.com

|Need more information with the P0171 TOYOTA code?

Need more information on how to fix the P0171 TOYOTA code?
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|P0171 TOYOTA code information for specific Toyota models

|Need help with a P0171 TOYOTA code?

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|P0171 TOYOTA code comments

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