P0171 Code – Meaning, Causes, and Fix

The P0171 code indicates that your engine is running too lean, meaning there is too much air and not enough fuel in the air-fuel mixture.

What Does P0171 Mean?

System Too Lean (Bank 1)

Your engine requires a balanced mixture of air and fuel. When this balance shifts toward too much air, performance and efficiency suffer.

Common Symptoms

• Check engine light

• Rough idle

• Hesitation during acceleration

• Poor engine performance

• Decreased fuel efficiency

What Causes P0171?

• Vacuum leaks

• Dirty or faulty mass airflow sensor (MAF)

• Weak fuel pump

• Clogged fuel filter

• Faulty oxygen sensor

• Leaking intake manifold

How to Fix P0171

Step 1: Inspect for vacuum leaks
Check hoses and intake connections.

Step 2: Clean the MAF sensor
Use proper MAF cleaner.

Step 3: Check fuel pressure
Low pressure can cause lean conditions.

Step 4: Replace faulty sensors
Oxygen or MAF sensors may need replacement.

Step 5: Inspect fuel system
Check injectors and fuel delivery components.

Is It Safe to Drive?

Short-term driving is usually okay, but long-term use can damage engine components.

Estimated Repair Cost

• MAF sensor cleaning: $10–$20

• Fuel pump: $300–$900

• O2 sensor: $100–$300

• Vacuum leak repair: $50–$300

FAQ

What happens if I ignore P0171?
The engine may overheat or suffer long-term damage.

Can a dirty air filter cause this?
Yes, restricted airflow can affect the air-fuel ratio.

Related Codes

• P0300 (Misfire)

• P0420 (Catalytic Efficiency)

• P0101 (MAF Sensor Issue)

Still not sure what your error means?
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IMPORTANT: This information is for general guidance only and may not apply to all models or situations. Always consult an official, technician, or representative from the product's company before attempting any repairs yourself.