P0174 on Chevrolet
System Too Lean (Bank 2)
P0174 on Chevrolet vehicles indicates system too lean (bank 2). Au7o has documented this code across 13 Chevrolet models — most commonly on Astro, Blazer S-10, C/K 1500. P0174 means the engine computer detected that the air-fuel mixture on Bank 2 (the side of the engine with cylinder 2) is running too lean — too much air relative to fuel. The computer monitors this through the oxygen/air-fuel sensors and fuel trims; when it has to add a large amount of extra fuel to compensate and still can't reach the target, it flags the mixture as too lean. A lean condition can cause rough idle, hesitation, or misfires, and over time can raise combustion temperatures. Because it's Bank 2 specific, an unmetered air leak on that bank or a fuel delivery shortfall is typical. Typical repair costs on Chevrolet range from $250 to $7,000, depending on the specific model and root cause.
Common Causes of P0174
- •Vacuum or intake air leak (hoses, gaskets, PCV)
- •Dirty or failing mass airflow (MAF) sensor
- •Weak fuel pump or restricted fuel filter (low fuel pressure)
- •Clogged or underperforming fuel injectors
- •Leaking intake manifold or throttle body gasket
- •Faulty or contaminated oxygen / air-fuel sensor
- •Exhaust leak upstream of the oxygen sensor
- •Stuck-open EGR valve
P0174 on Chevrolet by Model
Chevrolet Astro(2 issues)
- Central Port Injection (Spider) Fuel Leak1996-2005
The 4.3L Vortec V6 uses a central port fuel injection system (nicknamed "spider" for its appearance) that is prone to leaking fuel internally into the intake manifold. The fuel pressure regulator and poppet nozzles develop leaks, causing hard starting, rough idle, and a fuel smell. This is a fire hazard.
- 4.3L V6 Intake Manifold Gasket Leak1996-2005
Same intake gasket issue as all GM 4.3L vehicles. The composite gaskets fail, allowing coolant leaks. The Astro version is particularly problematic due to the engine positioned under the dash, making repairs more labor-intensive.
Chevrolet Blazer S-10(2 issues)
- 4.3L V6 Intake Manifold Gasket Leak1996-2005
Same as the S-10 truck - the 4.3L Vortec V6 develops intake manifold gasket leaks. The Blazer version is identical mechanically.
- Central Port Injection Fuel Leak Under Intake1992-1994
The early central port injection (CPI) system uses pressurized fuel lines under the upper intake manifold that develop cracks and leaks over time. Fuel leaks directly onto the hot engine, creating a serious fire hazard. The plastic fuel lines become brittle with age and heat exposure.
Chevrolet C/K 1500(1 issue)
- 5.7L Vortec Spider Injector Assembly Failure (CPI)1996-1998
The 5.7L Vortec V8 (1996-1999) uses a Central Port Injection (CPI) spider assembly with poppet nozzles that clog and leak fuel. The plastic fuel lines become brittle and crack, causing hard starts, rough idle, and fuel odor.
Chevrolet Cavalier(1 issue)
- 2.2L/2.4L Head Gasket Failure1995-2005
Both the 2.2L OHV and 2.4L Twin Cam engines in the Cavalier are prone to head gasket failure. The 2.4L is particularly susceptible due to the aluminum head and iron block thermal expansion differences.
Chevrolet Corsica(1 issue)
- Lower Intake Manifold Gasket Leak1990-1996
GM 3.1L V6 intake gaskets use a plastic carrier that warps and leaks coolant into the oil or externally. One of the most common failures on this engine across all GM platforms.
Chevrolet Equinox(2 issues)
- Excessive Oil Consumption (2.4L Piston Ring Defect)2010-2017
The 2.4L Ecotec engine uses low-tension piston rings that fail to maintain proper tension to keep oil in the crankcase. Vehicles consume 1 quart of oil per 800-1,000 miles. This defect can cause premature engine wear, engine failure, and potential fire risk if oil levels drop critically low. GM acknowledged this defect through TSBs and class action settlements.
- Engine Oil Leak Fire Risk (Oil Filter Adapter)2010-2017
A defective oil filter adapter can cause engine oil leaks that may contact hot exhaust components, creating a fire risk. Combined with the excessive oil consumption issue, low oil conditions can exacerbate the problem.
Chevrolet Express(1 issue)
- Intake Manifold Gasket Leak1996-2007
Vortec V8 intake manifold gaskets deteriorate causing coolant and oil leaks. Common on high-mileage vans, can lead to coolant contamination of oil if ignored.
Chevrolet Impala(1 issue)
- Intake Manifold Gasket Leak (3.4L/3.8L V6)2000-2005
The 3.4L and 3.8L V6 engines in 2000-2005 Impalas use Dex-Cool compatible intake manifold gaskets that deteriorate over time, causing coolant to leak externally or internally into the oil. External leaks appear as dried orange coolant trails on the engine block. Internal leaks contaminate the engine oil with coolant, turning it into a milky sludge that can destroy the engine bearings. This was one of the most widespread GM engine problems of the era and led to multiple class-action lawsuits.
Chevrolet Lumina(1 issue)
- 3.1L/3.4L V6 Intake Manifold Gasket Leak (Dex-Cool)1995-2001
The 3.1L and 3.4L pushrod V6 engines in the Lumina develop intake manifold gasket leaks, often attributed to Dex-Cool coolant reacting with the composite gaskets. Coolant leaks externally and can also enter the crankcase.
Chevrolet Monte Carlo(1 issue)
- 3.8L V6 Intake Manifold Gasket and Coolant Elbow Leak2000-2007
The 3.8L Series II V6 develops intake manifold gasket leaks and the plastic coolant elbow on the front of the engine cracks. The supercharged SS models also have supercharger snout wear causing boost leaks.
Chevrolet S-10(2 issues)
- 4.3L Vortec Central Sequential Fuel Injection (CSFI) Failure1996-2004
The "spider" fuel injection system in the 4.3L Vortec V6 uses a central injector assembly with poppet nozzles connected by fuel lines. The poppet nozzles stick and leak, causing rough running, hard starting, and fuel smell. The original design was replaced by an updated MPFI system that uses actual injectors at each port.
- 4.3L V6 Intake Manifold Gasket Leak1996-2004
The 4.3L Vortec V6 develops intake manifold gasket leaks that allow coolant to leak externally or mix with engine oil. The plastic gaskets deteriorate from heat cycling. This is a very common problem on all GM 4.3L V6 trucks.
Chevrolet Trailblazer(1 issue)
- 1.2L/1.3L Turbo Engine Oil Consumption2021-2026
The small-displacement turbo engines in the Trailblazer can consume oil between changes, particularly the 1.2L 3-cylinder. Some owners report needing to add oil between the 7,500-mile change intervals.
Chevrolet Uplander(1 issue)
- Intake Manifold Gasket Coolant Leak2005-2008
The 3.5L and 3.9L V6 develop intake manifold gasket leaks, continuing the GM V6 gasket legacy. Coolant leaks externally or into engine oil.
Looking for P0174 on a different make?
View P0174 across all makes →Frequently Asked Questions
What does P0174 mean on Chevrolet?▼
P0174 stands for "System Too Lean (Bank 2)." P0174 means the engine computer detected that the air-fuel mixture on Bank 2 (the side of the engine with cylinder 2) is running too lean — too much air relative to fuel. The computer monitors this through the oxygen/air-fuel sensors and fuel trims; when it has to add a large amount of extra fuel to compensate and still can't reach the target, it flags the mixture as too lean. A lean condition can cause rough idle, hesitation, or misfires, and over time can raise combustion temperatures. Because it's Bank 2 specific, an unmetered air leak on that bank or a fuel delivery shortfall is typical. On Chevrolet specifically, this code is documented across 13 models.
What causes P0174 on Chevrolet vehicles?▼
Common causes on Chevrolet: Vacuum or intake air leak (hoses, gaskets, PCV), Dirty or failing mass airflow (MAF) sensor, Weak fuel pump or restricted fuel filter (low fuel pressure), Clogged or underperforming fuel injectors, Leaking intake manifold or throttle body gasket. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0174 on a Chevrolet?▼
Repair costs on Chevrolet range from $250 to $7,000, depending on the specific model and root cause.
Which Chevrolet models have P0174 documented?▼
Au7o has documented P0174 on 13 Chevrolet models: Astro, Blazer S-10, C/K 1500, Cavalier, Corsica, Equinox, Express, Impala, Lumina, Monte Carlo, S-10, Trailblazer, Uplander.