p0171
Moderate
Honda · SUVs
System Too Lean Bank 1
Quick Answer
Error code P0171 on your Honda SUVs means: System Too Lean Bank 1. This is usually fixable — see the step-by-step guide below.
Affected Models
Likely Causes
  1. Vacuum leak in intake manifold, throttle body gasket, or PCV hoses
  2. Faulty or contaminated mass airflow (MAF) sensor
  3. Weak fuel pump or clogged fuel filter
  4. Dirty or clogged fuel injectors
  5. Cracked or disconnected vacuum line to brake booster
How to Fix It
1
Perform a smoke test to identify vacuum leaks in the intake system and around the throttle body
2
Clean the MAF sensor with MAF-specific cleaner; replace if readings remain out of specification on scan tool live data
3
Check fuel pressure at the fuel rail with a gauge; compare to Honda service manual specifications for the specific engine
4
Inspect and clean fuel injectors; replace any injectors with poor spray pattern or low flow
5
Verify all vacuum lines are intact and properly connected, especially the large brake booster hose
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
Throttle body gasket
MAF sensor
Fuel filter
Vacuum hoses and clamps
Related Error Codes
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