What does code P0171 mean on a Buick and is it safe to drive?
P0171: System Too Lean (Bank 1). Here's what it means on your Buick, what usually causes it, what repairs typically cost, and how safe it is to keep driving.
PowertrainMedium urgency
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 for your Buick
- 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 Buick, repairs for P0171 often fall between $50 and $500, depending on the cause and whether you use OEM or aftermarket parts. Labor rates vary by location.
Known issues on Buick
Buick P0171 on 3.8L V6 engines is frequently caused by a leaking lower intake manifold gasket—a well-known failure on the 3800 Series engine. The MAF sensor is the second most common culprit.
Most commonly affected models
Enclave 2008–2012LaCrosse 2005–2009Rendezvous 2002–2007