What P0174 Means on Your 2022 GMC Terrain
A P0174 code on your 2022 GMC Terrain indicates the engine control module has detected a lean air-fuel condition on Bank 2. The 2022 Terrain is powered by a 1.5L turbocharged four-cylinder engine producing 170 horsepower. As an inline-four engine with one cylinder bank, P0174 flags when the lean fuel trim correction exceeds its normal limits.
The Terrain's small turbo engine is efficient but sensitive to air-fuel ratio issues. A lean condition can cause reduced performance and potential engine damage if ignored.
Symptoms
- Check engine light on
- Rough or unsteady idle
- Hesitation during acceleration
- Reduced fuel economy
- Turbo boost may feel diminished
- Possible stalling at idle
Common Causes
- Boost Leak (35% likelihood) – The 1.5T has charge pipe connections, intercooler hoses, and turbo outlet fittings that can loosen or crack. Any leak after the MAF sensor causes lean running.
- MAF Sensor Contamination (25% likelihood) – Oil vapor or dirt on the MAF hot wire leads to underreported airflow and lean fueling.
- Fuel Delivery Issue (20% likelihood) – Weak fuel pump, clogged injector, or fuel pressure regulator failure reduces fuel supply.
- PCV System Leak (20% likelihood) – A failed PCV valve or cracked hose creates an internal vacuum leak.
Diagnosis
- Scan for all codes – Look for P0171, boost codes, and misfire codes.
- Monitor fuel trims – LTFT above +15% confirms lean running.
- Boost leak test – Pressurize the intake to find leaks in turbo plumbing.
- MAF sensor test – Clean and compare to GM specifications.
- Fuel pressure test – Verify pump output and rail pressure.
Repair Costs
- Boost leak repair – $80–$350.
- MAF sensor – Cleaning: $10. Replacement: $80–$220.
- Fuel pump – $280–$500.
- PCV valve – $40–$120.
- Fuel injector – $150–$400.
DIY Feasibility
The Terrain's compact engine bay limits access somewhat, but basic tasks are still doable. MAF cleaning takes 15 minutes. Visual inspection of boost hoses is straightforward. Fuel system work and proper boost leak testing require specialized tools and are better handled professionally.
Prevention
- Replace the air filter per GM's schedule
- Use Top Tier gasoline
- Inspect boost hoses and connections during oil changes
- Address any idle or power changes early
- Follow GM's maintenance intervals