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AutoCodes - Generic - P0171

P0171 Code - Fuel Trim System Lean Bank 1

- Code Popularity: 485,501 Views
- Repair Importance Level: 3/3
- Repair Difficulty Level: 3/3
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By AutoCodes.com - Updated May 29, 2022
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|P0171 code possible causes

  • Dirty or Restricted Air Filter
  • Dirty or Faulty Mass Air Flow (MAF) Sensor
  • Intake Air Leaks
  • Exhaust Gas Leaks
  • Fuel Contamination
  • Faulty or Clogged Fuel Injectors
  • Faulty Front Heated Oxygen Sensor
  • Ignition Misfiring
  • Low Fuel Pressure
  • Positive Crankcase Ventilation (PCV) Hose Leaks

|How do I fix code P0171 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.

Does your car have Safety Recalls? → Check here

|P0171 code tech notes

The P0171 code means that more air than gasoline is detected in the exhaust gases exiting the combustion chamber. If the P0171 is set in along with the P0174 code, it is highly 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 Mass Air Flow (MAF) Sensor. If the problem persists the MAF or Front Heated Oxygen (O2) Sensor will need to be replaced.

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|Cost of diagnosing P0171 code

Labor: 1.0

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

|What are P0171 code possible symptoms?

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

|P0171 code description

The Engine Control Module (ECM) controls a Closed Loop air/fuel metering system to provide the best possible combination of drivability, fuel economy, and emission control. The ECM monitors the Heated Oxygen Sensor (HO2S) signal voltage and adjusts the fuel delivery based on the signal voltage while in Closed Loop. A change made to the fuel delivery changes the long and short-term fuel trim values. The short-term fuel trim values change rapidly in response to the HO2S signal voltages. These changes fine-tune the engine fueling. The long-term fuel trim values change in response to trends in the short-term fuel trim. The long-term fuel trim makes coarse adjustments to fueling to re-center and restore control to short-term fuel trim. The ideal fuel trim values are around 0 %. A positive fuel trim value indicates that the ECM is adding fuel to compensate for a lean condition. A negative fuel trim value indicates that the ECM is reducing the amount of fuel to compensate for a rich condition. The Diagnostic Trouble Code (DTC) will be set when the average long-term fuel trim weighted average value is greater or less than a calibrated value.

OBDII Code p0171 - Fuel Trim System Lean Bank 1 - AutoCodes.com
P0171 Code - Fuel Trim System Lean Bank 1

|Need more information with the P0171 code?

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|Need help with a P0171 code?

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|P0171 code comments

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