What Does P0172 Mean on Your 2022 Buick Envision?
A P0172 code on your 2022 Buick Envision means the engine control module has detected a rich air-fuel mixture. The 2022 Envision is powered by a 2.0-liter turbocharged 4-cylinder engine producing 228 horsepower, paired with a 9-speed automatic transmission. As an inline-4, there is only one cylinder bank, so P0172 affects the entire engine.
A rich condition means the engine is receiving more fuel than the optimal 14.7:1 air-fuel ratio requires. This hurts gas mileage, increases emissions, and can damage the catalytic converter over time.
Symptoms You May Notice
- Check engine light on
- Fuel economy below the rated 24/31 mpg
- Rough or shaky idle
- Black smoke from the exhaust
- Fuel smell at the tailpipe
- Reduced power or hesitation
- Potential misfires
Common Causes of P0172 on the 2022 Buick Envision
- Dirty MAF Sensor - The 2.0T engine's MAF sensor can become contaminated with oil vapor from the turbo system. A dirty MAF causes incorrect airflow readings and over-fueling.
- EVAP Purge Valve Stuck Open - A well-known GM issue. The purge valve fails to close properly, continuously drawing fuel vapors into the intake.
- Boost System Leak - Leaking charge pipes, intercooler connections, or a faulty bypass valve reduce actual boost pressure reaching the engine.
- Faulty Upstream O2 Sensor - A degraded oxygen sensor provides inaccurate exhaust readings, causing the ECM to over-fuel.
How to Diagnose P0172
- Pull all codes - Check for EVAP, MAF, boost, or O2 sensor companion codes.
- Review fuel trims - Negative LTFT beyond -10% confirms excess fuel delivery.
- Clean the MAF sensor - Always the best and cheapest first step.
- Test the purge valve - Check for proper open/close function with a vacuum test.
- Inspect the boost system - Check all charge pipes and intercooler hoses for leaks.
- Monitor O2 sensor data - Check upstream sensor response and voltage range.
Repair Options and Cost Breakdown
- MAF Sensor Cleaning - $12-$25 DIY with spray cleaner.
- MAF Sensor Replacement - $120-$270 parts and labor.
- EVAP Purge Valve - $75-$190 parts and labor.
- Boost Hose Repair - $60-$280 depending on the component.
- Fuel Injector Replacement - $250-$500 per injector.
- O2 Sensor Replacement - $150-$300 parts and labor.
Most P0172 repairs on the Envision cost between $100 and $320. GM parts are reasonably priced for this midsize crossover.
Can You DIY This Repair?
Yes, several fixes are DIY-friendly. MAF sensor cleaning is a 10-minute job. The EVAP purge valve is easy to replace on most GM vehicles. Boost hose inspection is straightforward. Fuel injector work on the turbocharged direct injection engine is more complex and best left to a professional.
Prevention Tips
- Replace the air filter every 15,000-20,000 miles
- Use quality fuel from top-tier stations
- Add fuel system cleaner every 10,000 miles
- Inspect boost hose connections during oil changes
- Address check engine lights promptly