P0171 P0171 Fuel Trim System Too Lean (Bank 1)
What P0171 means for you
Both sources align on a low severity.
Symptoms
- The Check Engine Light will illuminate.
- You may experience a lack of power during acceleration, along with possible misfiring or 'coughing' sounds.
- Idling issues may occur, particularly when the engine is warm or at a stoplight.
- Stalling might happen when the engine struggles to maintain a steady idle.
- A hissing noise could be heard from the engine bay if a vacuum leak is present.
- The engine may have difficulty starting due to insufficient fuel in the combustion chamber.
Common causes
- The primary reason for the P0171 code is unmetered air entering the engine's combustion system.
- Common culprits include malfunctioning mass airflow sensors, weak fuel pumps, and clogged fuel filters or injectors.
- Defective oxygen sensors can also contribute to the engine running either lean or rich.
- Exhaust leaks may trigger the P0171 code, indicating an imbalance in the air-fuel mixture.
- For vehicles with multiple banks, issues like a faulty fuel injector on Bank 1 can lead to excessive fuel entering the combustion chamber.
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Send your ECUWhat this code means
The P0171 code indicates that the engine control module (PCM) has detected a lean air-to-fuel mixture in the combustion chamber, meaning there is too much air relative to the amount of fuel. This imbalance can lead to performance issues, as the PCM attempts to compensate by increasing fuel delivery. If the necessary adjustments exceed predefined limits, the P0171 code will be triggered, often accompanied by the Check Engine Light.
Frequently asked questions
While you can drive with a P0171 code, it is not advisable due to potential engine performance issues.
Repair costs can vary widely, but addressing common issues like a mass airflow sensor or fuel injector may range from $100 to $500.
Ignoring a P0171 code can lead to decreased fuel efficiency, increased emissions, and potential long-term engine damage.
