2012 Infiniti P0171: What It Means & Is It Safe to Drive?
P0171 on the 2012 Infiniti: System Too Lean (Bank 1). Here's what it means, what usually causes it, what repairs typically cost, and whether it's safe to keep driving.
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What this code means
The engine is getting too much air relative to fuel. The O2 sensor sees excess oxygen in the exhaust and the PCM is adding more fuel than normal to compensate.
Common causes on the 2012 Infiniti
- Dirty or faulty mass airflow (MAF) sensor
- Vacuum leaks (PCV hose, intake gasket, brake booster)
- Weak fuel pump or clogged fuel filter
- Leaking or stuck open fuel injectors (less common)
Symptoms
- Check Engine Light
- Rough idle, hesitation, lack of power
- Possible spark knock under load
- Poor fuel economy
Typical fixes
- Clean or replace MAF sensor
- Locate and seal vacuum leaks
- Replace fuel filter / test fuel pressure
- Smoke test intake system
Repair cost range
For a 2012 Infiniti, repairs for P0171 typically fall between $50 and $500, depending on the root cause and labor rates in your area.
Known issues on Infiniti
P0171 on Infiniti VQ35 engines often results from a sticking EVAP purge valve drawing unmetered air. MAF sensor contamination is the second most common cause on high-mileage G35 and FX35 models.
Most commonly affected models
G35 2003–2006G37 2008–2013FX35 2003–2008