What Does P0172 Mean on Your 2024 Buick Encore GX?
A P0172 code on your 2024 Buick Encore GX means the ECM has detected that the air-fuel mixture is running too rich. The 2024 Encore GX features a 1.2-liter turbocharged 3-cylinder engine producing 137 horsepower paired with a CVT. Since this is an inline engine with only one bank, P0172 affects the entire engine.
Too rich means there is more fuel than the ideal 14.7:1 ratio requires. The ECM uses oxygen sensor data to maintain the correct mixture, and when it cannot correct a persistent rich condition, it sets P0172.
Symptoms You May Notice
- Check engine light on
- Reduced fuel economy below the rated 30/32 mpg
- Rough or unsteady idle
- Black exhaust smoke
- Fuel odor from the exhaust
- Hesitation or lack of power
- Engine running rougher than normal
Common Causes of P0172 on the 2024 Buick Encore GX
- Dirty MAF Sensor - Oil vapor contamination from the turbo system is the leading cause. The MAF underreads airflow, prompting the ECM to inject too much fuel.
- EVAP Purge Valve Failure - A stuck-open purge valve is a well-known GM issue that continuously feeds fuel vapors into the intake.
- Boost System Leak - Charge pipe or intercooler hose leaks allow pressurized air to escape, reducing actual airflow to the engine.
- Faulty Upstream O2 Sensor - A slow or biased oxygen sensor can cause the ECM to over-correct with extra fuel.
How to Diagnose P0172
- Scan all codes - Look for EVAP, MAF, boost, or O2 companion codes.
- Review fuel trims - Negative LTFT beyond -10% confirms the rich condition.
- Clean the MAF sensor - Always the best first step.
- Test the purge valve - Check for proper open and close function.
- Inspect boost system - Check all hoses and clamps for leaks.
- Monitor O2 sensor - Check response time and voltage range.
Repair Options and Cost Breakdown
- MAF Sensor Cleaning - $10-$20 DIY with spray.
- MAF Sensor Replacement - $110-$250 parts and labor.
- EVAP Purge Valve Replacement - $70-$190 parts and labor.
- Boost Hose Repair - $50-$260 depending on the component.
- Fuel Injector Replacement - $200-$420 per injector.
- O2 Sensor Replacement - $140-$290 parts and labor.
Most P0172 repairs on the 2024 Encore GX cost $80 to $300. This compact crossover benefits from affordable GM parts and straightforward service.
Can You DIY This Repair?
Many repairs are very DIY-friendly on the Encore GX. The engine bay is compact but accessible. MAF cleaning, purge valve replacement, and basic boost hose inspections can all be done at home with standard tools. Injector work is more complex and better suited for a professional.
Prevention Tips
- Replace the air filter every 15,000 miles
- Use quality fuel from reputable stations
- Add fuel system cleaner every 10,000 miles
- Inspect turbo hose connections during routine maintenance
- Address check engine lights promptly