Understanding P0174 on Your 2022 GMC Sierra
A P0174 code on your 2022 GMC Sierra indicates Bank 2 is running with a lean air-fuel mixture. The 2022 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). The ECM has detected that lean fuel trim corrections have exceeded normal limits on that bank.
The Sierra is a workhorse truck, and a lean condition affects its ability to deliver consistent power. Let's track down the cause.
Symptoms
- Check engine light on
- Rough or uneven idle
- Power loss during acceleration
- Worse fuel economy
- Engine hesitation
- Possible knocking under load
Common Causes
- Vacuum Leak (30% likelihood) – Intake manifold gaskets, PCV hoses, and brake booster lines can develop leaks. GM V8 intake manifolds have multiple sealing surfaces.
- Fuel Injector Problem (25% likelihood) – Clogged or failing injectors on Bank 2. AFM/DFM-equipped engines can develop carbon buildup on deactivation-capable injectors.
- MAF Sensor Issue (25% likelihood) – Contamination from oil vapor or dirt causes the MAF to underreport airflow.
- Exhaust Leak on Bank 2 (20% likelihood) – Manifold gasket or cracked manifold allowing air ingestion near the O2 sensor.
Diagnosis
- Compare bank fuel trims – If only Bank 2 LTFT is elevated, focus on bank-specific causes.
- Smoke test the intake – Find hidden vacuum leaks.
- Test fuel injectors – Balance test or noid light check on Bank 2 cylinders.
- Clean and test MAF – Compare readings to GM specifications.
- Inspect exhaust manifolds – Look for leaks on the driver side.
Repair Costs
- Vacuum leak – $80–$500. Intake gasket: $300–$650.
- Fuel injector – Single: $100–$250. Labor: $150–$350.
- MAF sensor – Cleaning: $10. Replacement: $80–$250.
- Exhaust manifold – $200–$800.
DIY Options
The Sierra's large engine bay gives good access. MAF cleaning takes 15 minutes. Listening for vacuum leaks and checking hoses is straightforward. Intake manifold gasket replacement on a GM V8 is an intermediate job. Exhaust manifold work may require penetrating oil and patience with rusty bolts.
Prevention
- Use Top Tier fuel to keep injectors clean
- Replace the air filter per schedule
- Inspect intake and exhaust components regularly
- Consider fuel injector cleaning every 50,000 miles
- Address drivability changes early