Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
Your car's engine is not getting enough fuel on one side, so it can't run properly. It's like trying to run a race without enough energy.
The engine control module (ECM) has detected that the air-fuel mixture on bank 1 is too lean, meaning there is too much air and not enough fuel.
P0171 indicates that the fuel system is running lean on bank 1, which is the side of the engine containing cylinder number 1. This is often due to an imbalance in the air-to-fuel ratio, where there is more air than fuel being burned in the combustion process.
• Check Engine Light is on
• Poor fuel economy
• Rough idle
• Vacuum leaks
• Faulty mass air flow (MAF) sensor
• Clogged fuel injectors
ECM: Engine Control Module
MAF Sensor: Mass Air Flow Sensor
• Check for vacuum leaks
• Inspect the MAF sensor
• Examine fuel injectors for clogs
• Fix any vacuum leaks
• Clean or replace the MAF sensor
• Clean or replace fuel injectors
• OBD-II scanner
• Vacuum gauge
• Fuel injector cleaning kit
$100 - $300
Moderate
• Toyota Camry
• Ford F-150
• Honda Accord
• Regular maintenance checks
• Timely replacement of air filters
• Use quality fuel
Engine Performance
• Do not ignore the Check Engine Light
• Have your vehicle inspected by a professional
• Regularly maintain your vehicle to prevent recurrence
Check with your vehicle manufacturer for warranty coverage on engine components.
P0171 is a common code that has been reported frequently in vehicles with high mileage or those that have not been maintained regularly.
Moderate – Should be addressed soon to avoid potential engine damage.
Driving with a lean condition can lead to increased emissions and potential engine damage.
• Engine at operating temperature
• Vehicle in closed loop mode
Bank 1 is typically the side of the engine with cylinder number 1, often found on the driver's side in a V-type engine.
Q: What does 'lean' mean in car terms?
A: Lean means there is too much air and not enough fuel in the engine's air-fuel mixture.
Q: Can I drive with a P0171 code?
A: It's possible to drive, but it's not recommended as it can lead to engine damage over time.
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Fitment Required · Vehicle-fitment part
Relevant for airflow, fuel-trim, and intake-metering faults after confirming the sensor is actually at fault.
Airflow and fuel-trim codes can involve the mass air flow sensor after proper diagnosis.
Verify the sensor design and fitment for your exact vehicle.
View options on AmazonThese parts may be related to this fault category, but a code by itself does not confirm exact fitment or guarantee that replacing a part will solve the problem.