What does Error Code P0171 mean?
Moderate Issue
DTC Code P0171 indicates a Fuel Trim System Lean condition on Bank 1, where the Engine Control Module (ECM) detects a lean air/fuel mixture and adjusts the fuel delivery to compensate.
What are the symptoms of Error Code P0171?
- Engine Light ON: The check engine light or service engine soon warning light illuminates, indicating a potential issue with the fuel trim system on bank 1.
- Excessive Fuel Consumption: The vehicle may consume more fuel than usual, which can be linked to a lean condition in the fuel trim system on bank 1.
What causes Error Code P0171?
- The air filter may be dirty or restricted, causing insufficient air intake and leading to a lean condition.
- A dirty or faulty Mass Air Flow (MAF) sensor can provide incorrect air flow readings, affecting the air-fuel mixture.
- Intake air leaks can introduce unmetered air into the system, resulting in a lean mixture.
- Exhaust gas leaks before the oxygen sensor can cause incorrect readings, affecting fuel trim.
- Fuel contamination can alter the combustion process, leading to a lean condition.
- Faulty or clogged fuel injectors may not deliver the correct amount of fuel, causing a lean mixture.
- A faulty front heated oxygen sensor can provide inaccurate data, affecting fuel adjustments.
- Ignition misfiring can lead to incomplete combustion, affecting the air-fuel ratio.
- Low fuel pressure can result in insufficient fuel delivery, causing a lean condition.
- Leaks in the Positive Crankcase Ventilation (PCV) hose can introduce unmetered air, affecting the mixture.
Find the Root Cause with AI
Analyze symptoms and error codes with artificial intelligence for a precise diagnosis
Fast Diagnosis in under 3 minutes
Precise AI-powered analysis
Free No hidden fees
Data-Driven Over 40,000 reference cases
How to fix Error Code P0171?
- Initial Inspection: Check for any additional DTCs, especially P0174, which may indicate an intake leak. Inspect the intake system for any visible leaks or damage.
- Air Filter and MAF Sensor: Inspect the air filter for dirt or blockage and replace if necessary. Clean the Mass Air Flow (MAF) sensor using appropriate cleaner to ensure accurate readings.
- Check for Vacuum Leaks: Perform a thorough inspection for vacuum leaks in hoses and connections. Use a smoke machine if available to detect any hidden leaks.
- Fuel System Inspection: Check the fuel pressure and ensure it is within specifications. Inspect the fuel injectors for proper operation and cleanliness.
- Oxygen Sensor Evaluation: Test the Front Heated Oxygen (O2) Sensor for proper function. Replace if the sensor is faulty or not responding correctly.
- ECM and Wiring Check: Inspect the Engine Control Module (ECM) and related wiring for any signs of damage or corrosion that could affect sensor readings.