What Does P0172 Mean on Your 2022 Buick Encore GX?
A P0172 trouble code on your 2022 Buick Encore GX means the engine control module (ECM) has detected a rich air-fuel mixture on Bank 1. The 2022 Encore GX is available with two engine options: a 1.2-liter turbocharged 3-cylinder producing 137 hp and a 1.3-liter turbocharged 3-cylinder producing 155 hp. Both are inline engines with a single bank, so P0172 affects the entire engine.
Running rich means the engine is receiving more fuel than the ideal 14.7:1 stoichiometric ratio. This wastes gas, raises emissions, and can cause long-term damage to the catalytic converter.
Symptoms You May Notice
- Check engine light illuminated
- Fuel economy worse than the rated 30/32 mpg (1.2T) or 29/31 mpg (1.3T)
- Rough or unstable idle
- Black exhaust smoke
- Fuel smell from the exhaust
- Hesitation under acceleration
- Possible engine misfires
Common Causes of P0172 on the 2022 Buick Encore GX
- Dirty MAF Sensor - The small turbo engines are sensitive to MAF contamination. Oil mist from the turbo inlet can coat the sensor element, causing inaccurate airflow readings.
- EVAP Purge Valve Stuck Open - A common GM issue. The purge valve fails to close, allowing continuous fuel vapor into the intake manifold and enriching the mixture.
- Boost Leak - The turbocharged 3-cylinder engines use charge pipes and an intercooler. Any leak reduces actual airflow while the ECM fuels for expected boost levels.
- Failing O2 Sensor - A slow-responding upstream oxygen sensor can provide incorrect data, causing the ECM to over-fuel.
How to Diagnose P0172
- Scan all codes - Check for EVAP, MAF, boost, or O2 sensor companion codes.
- Check fuel trim data - Negative LTFT values beyond -10% confirm rich running.
- Clean the MAF sensor - The cheapest and easiest first step.
- Test the EVAP purge valve - Verify proper operation with a vacuum test.
- Check boost system - Inspect charge pipes and connections for leaks.
- Monitor O2 sensor data - Check upstream sensor response time and voltage range.
Repair Options and Cost Breakdown
- MAF Sensor Cleaning - $10-$20 for spray. Quick 10-minute DIY.
- MAF Sensor Replacement - $100-$240 parts and labor.
- EVAP Purge Valve Replacement - $70-$180 parts and labor.
- Boost Hose Repair - $50-$250 depending on the component.
- Fuel Injector Replacement - $200-$400 per injector with labor.
- O2 Sensor Replacement - $130-$280 parts and labor.
Most P0172 repairs on the Encore GX cost between $80 and $280. This is a compact crossover with affordable GM parts.
Can You DIY This Repair?
Yes, many fixes are DIY-friendly. The Encore GX has a compact but accessible engine bay. MAF cleaning, purge valve replacement, and air filter changes are all straightforward at-home repairs. The 3-cylinder turbo engines are relatively simple compared to V6 or V8 configurations.
Prevention Tips
- Replace the engine air filter every 15,000 miles
- Use quality fuel from top-tier gas stations
- Add fuel system cleaner every 10,000 miles
- Inspect turbo hose connections during oil changes
- Do not ignore check engine lights