p0171
Moderate
Mazda · Sedans
System Too Lean Bank 1
Quick Answer
Error code P0171 on your Mazda Sedans means: System Too Lean Bank 1. This is usually fixable — see the step-by-step guide below.
Affected Models
Likely Causes
How to Fix It
1
Connect OBD-II scanner to diagnose fault code
2
Inspect fuel injectors and oxygen sensors for damage
3
Check fuel pressure using fuel pressure gauge
4
Perform smoke test to identify vacuum leaks
5
Clear codes after repair and perform test drive
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
Oxygen sensor
Fuel injectors
Fuel filter
Intake gaskets
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