What P0174 Means on Your 2021 Chevrolet Tahoe
The P0174 code on your 2021 Chevy Tahoe indicates that Bank 2 of the engine is running too lean. The 2021 Tahoe is the first year of the fifth generation and offers a 5.3L EcoTec3 V8 or a 6.2L EcoTec3 V8 (with a 3.0L Duramax diesel also available). On both V8 engines, Bank 2 is the driver-side cylinder bank. A lean condition means the air-fuel mixture has too much air relative to fuel, and the ECM has run out of adjustment range.
Common Symptoms
- Check engine light on
- Rough or vibrating idle
- Hesitation when accelerating
- Reduced towing capability
- Decreased fuel economy
- Engine surging at highway speeds
Top Causes for the 2021 Tahoe
- Intake Manifold or Vacuum Leak (30% likelihood) - The composite intake manifold on the V8 engines can develop gasket leaks. Vacuum hoses in the engine bay can also crack.
- MAF Sensor Issue (25% likelihood) - A contaminated or failing MAF sensor sends incorrect airflow data to the ECM.
- Fuel Injector Problem (25% likelihood) - The direct injection system on the 5.3L and 6.2L V8s can develop individual injector flow restrictions.
- Fuel Pressure Issue (20% likelihood) - A weakening fuel pump or fuel pressure regulator can reduce fuel delivery below required levels.
Diagnosis Steps
- Read all codes - Check for P0171 and misfire codes. Both banks lean suggests MAF or fuel system.
- Smoke test - Identify vacuum and intake manifold leaks.
- Test MAF sensor - The 5.3L should read about 10-16 g/s at idle; the 6.2L about 12-18 g/s.
- Check fuel pressure - Verify rail pressure at idle and under load.
- Test fuel injectors - Check injector balance and flow rates.
Repair Cost Estimates
- Intake manifold gasket - $300 to $600. Higher labor costs due to the Tahoe's engine bay configuration.
- MAF sensor replacement - $140 to $340 with labor.
- Fuel injector service - $200 to $500 for cleaning, $500 to $1,100 for replacement.
- Fuel pump replacement - $450 to $900.
Warranty and Driving
Your 2021 Tahoe should still be under the 5-year/60,000-mile powertrain warranty. Check with your dealer. Avoid towing with the lean condition active to prevent expensive catalytic converter damage.
Prevention Tips
- Use OEM air filters
- Clean the MAF sensor every 25,000 miles
- Use Top Tier fuel
- Inspect vacuum hoses during oil changes
- Follow GM's maintenance schedule