What P0174 Means on Your 2024 GMC Sierra
When your 2024 GMC Sierra displays a P0174 code, the engine control module has detected that Bank 2 is running too lean. The 2024 Sierra offers the 2.7L turbo-four (310 hp), 5.3L V8 (355 hp), and 6.2L V8 (420 hp). On the V8 engines, Bank 2 is the driver side (left side) of the engine. P0174 indicates too much air or insufficient fuel on that bank.
A lean condition on a full-size truck affects performance and fuel economy. If you tow or haul regularly, this needs prompt resolution.
Symptoms
- Check engine light on
- Rough idle
- Reduced power during acceleration
- Increased fuel consumption
- Engine hesitation under load
- Possible knock or ping under throttle
Common Causes
- Vacuum Leak (30% likelihood) – Intake manifold gaskets and vacuum hoses can leak. GM's Active Fuel Management (AFM) or Dynamic Fuel Management (DFM) system adds complexity to the intake system.
- Fuel Injector Issue (25% likelihood) – A clogged or failed injector on Bank 2. DFM-equipped engines have injectors that cycle on and off, which can lead to carbon buildup.
- MAF Sensor Contamination (25% likelihood) – A dirty MAF sensor underreports airflow, causing lean fueling.
- Exhaust Leak (20% likelihood) – An exhaust manifold gasket leak or cracked manifold on Bank 2 can allow air ingestion past the O2 sensor.
Diagnosis
- Check warranty and TSBs – GM may have service bulletins for lean codes on 2024 Sierra models.
- Compare bank fuel trims – Identify if the lean condition is specific to Bank 2 or both banks.
- Smoke test – Find vacuum leaks in the intake system.
- Test injectors – Verify proper operation, especially on DFM cylinders.
- Inspect exhaust manifolds – Check for leaks on the driver side.
Repair Costs
- Vacuum leak repair – $80–$500. Intake manifold gasket: $300–$700.
- Fuel injector – Single: $100–$250. Labor: $200–$400.
- MAF sensor – Cleaning: $10. Replacement: $80–$250.
- Exhaust manifold – Gasket: $150–$350. Manifold: $350–$800.
The 2024 Sierra is covered by GM's 3-year/36,000-mile bumper-to-bumper warranty and 5-year/60,000-mile powertrain warranty.
Dealer or DIY?
Under warranty, the dealer should handle this at no cost. They have GM's GDS2 diagnostic system for accurate diagnosis. If out of warranty, MAF cleaning and visual inspections are easy DIY jobs. Intake gasket and injector work require more tools and experience.
Prevention
- Use Top Tier gasoline to prevent injector buildup
- Replace the air filter per GM's schedule
- Inspect intake and exhaust components during oil changes
- Consider fuel system cleaning every 50,000 miles
- Follow GM's recommended service intervals