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p0171
Moderate
Acura · Sedans
System Too Lean (Bank 1)
Quick Answer
Error code P0171 on your Acura Sedans means: System Too Lean (Bank 1). This is usually fixable — see the step-by-step guide below.
Affected Models
Applies to all models
DE3/DE4DC5/DN2DN2NC1KC1UA6CU2
Likely Causes
  1. Faulty oxygen sensor
  2. Fuel pressure regulator malfunction
  3. Vacuum leak in intake manifold
  4. Clogged fuel injector
  5. Mass airflow sensor failure
How to Fix It
1
Read and clear fault codes with diagnostic scanner
2
Inspect vacuum lines for cracks or disconnections
3
Check fuel pressure using fuel pressure gauge
4
Test oxygen sensor voltage with multimeter
5
Inspect fuel injectors for blockage
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
Replacement oxygen sensor
Fuel pressure gauge
Fuel injector cleaner
Related Error Codes
P0300P0301P0420P0325P0341
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