What Does P0171 Mean on Your 2022 Buick Envision?
If your 2022 Buick Envision has triggered a P0171 trouble code, the engine control module has detected a lean air-fuel mixture on Bank 1. The 2022 Envision is powered by a 2.0-liter turbocharged four-cylinder engine (LSY) producing 228 horsepower. Since this is an inline four-cylinder, there's only one bank. The ECM is detecting that the air-fuel ratio is skewed toward too much air or insufficient fuel.
Symptoms You Might Notice
- Check engine light on the dashboard
- Rough or uneven idle
- Hesitation or stumble when accelerating
- Reduced fuel economy below the normal 26-31 MPG range
- Engine may feel less responsive than usual
- Possible surging at steady cruising speeds
Common Causes of P0171 on the 2022 Buick Envision
GM's 2.0-liter turbo engine is generally reliable, but a few common issues can trigger this code:
- Vacuum or Boost Leak (35% likelihood) — Check the charge pipe connections, intercooler hoses, intake manifold gasket, and PCV valve hoses. The turbo plumbing has several potential leak points.
- MAF Sensor Contamination (30% likelihood) — Oil vapors from the PCV system or a dirty air filter can coat the MAF sensor element, causing inaccurate airflow readings.
- Fuel Injector Issue (20% likelihood) — A clogged or malfunctioning direct fuel injector can reduce fuel delivery to one or more cylinders.
- Weak Fuel Pump (15% likelihood) — The in-tank fuel pump may not be maintaining adequate pressure, particularly under boost.
How to Diagnose the Problem
- Full code scan — Use an OBD-II scanner to check for additional codes. Misfire codes alongside P0171 can narrow down the problem cylinder.
- Monitor fuel trims — Check STFT and LTFT at idle and under load. Consistent positive trims above 10% confirm a lean condition.
- Inspect turbo plumbing — Visually check all charge pipes, clamps, and hose connections. Listen for hissing sounds with the engine running.
- Smoke test — The most effective way to pinpoint vacuum and boost leaks.
- Check fuel pressure — Monitor fuel rail pressure during different operating conditions using a scan tool.
Repair Options and Cost Breakdown
- Vacuum or boost leak repair: $100–$300. DIY cost is $15–$60. Straightforward if you can locate the leak.
- MAF sensor replacement: $120–$250. Parts cost $45–$100. Easy 15-minute DIY job.
- Fuel injector service or replacement: $250–$600. Professional cleaning runs $80–$150. Full replacement is $400–$700 for all four.
- Fuel pump replacement: $350–$700. Parts cost $180–$350. Requires dropping the fuel tank.
Prevention Tips
- Use Top Tier gasoline for cleaner fuel injectors
- Replace the air filter every 15,000–20,000 miles
- Follow GM's maintenance schedule for the 2.0T engine
- Address any unusual engine sounds or performance issues promptly
- Use the recommended oil specification to protect the turbo and PCV system
Should You Worry?
P0171 is a moderate concern. Your Envision is safe for daily commuting, but prolonged lean running can damage the catalytic converter and increase wear on the turbocharger. Plan to have it diagnosed within a couple of weeks.