Engine-Codes - Toyota - P0171 2005 Toyota Corolla

P0171 2005 Toyota Corolla Code - Air/Fuel Mixture System Lean Bank 1

- Code Popularity: 41,548 Views
- Repair Importance Level: 3/3
- Repair Difficulty Level: 3/3
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What are the Possible Causes of the DTC P0171 2005 Toyota Corolla?

NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other 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

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.

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









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How to Fix the DTC P0171 2005 Toyota Corolla?

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 pins.

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What is the Cost to Diagnose the Code?

Labor: 1.0

The cost to diagnose the P0171 2005 Toyota Corolla code is 1.0 hour of labor. The diagnosis time and labor rates at auto repair shops vary depending on the location, make and model of the vehicle, and even the engine type. Most auto repair shops charge between $75 and $150 per hour.

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.)

What are Code Possible Symptoms?

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

What Does the P0171 2005 Toyota Corolla Code Mean?

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).

P0171 2005 Toyota Corolla Code - Air/Fuel Mixture System Lean Bank 1

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