p0171
Moderate
Honda · Sedans
System Too Lean Bank 1
Quick Answer
Error code P0171 on your Honda Sedans means: System Too Lean Bank 1. This is usually fixable — see the step-by-step guide below.
Affected Models
Applies to all models
CV3CV4FC1FC4FE1FL5ZC5Accord EX 2024Accord EX-L 2024Accord Hybrid EX-L 2024Accord Hybrid Sport 2024Accord Hybrid Touring 2024Accord LX 2024Accord Sport 2024Accord Touring 2024Civic EX 2024Civic Hybrid Sport 2025Civic Hybrid Sport Touring 2025Civic LX 2024Civic Si 2024Civic Sport 2024Civic Touring 2024Civic Type R 2024ZE4
Likely Causes
How to Fix It
1
Use a smoke machine or carb cleaner to check for vacuum leaks around the intake manifold and hoses
2
Remove and clean the MAF sensor with MAF-specific cleaner; replace if readings are out of specification
3
Check fuel pressure with a fuel pressure gauge; compare to Honda service manual specifications
4
Inspect and clean fuel injectors; consider professional ultrasonic cleaning if buildup is severe
5
Check for exhaust leaks upstream of the primary oxygen sensor and repair as needed
Pro Tip
This fix requires some technical knowledge. If you're unsure about any step, consider contacting support or a qualified technician.
Parts You May Need
Intake manifold gasket
Vacuum hoses
MAF sensor
Fuel filter
Fuel injector O-rings
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