P0174 on Nissan
System Too Lean (Bank 2)
P0174 on Nissan vehicles indicates system too lean (bank 2). Au7o has documented this code across 7 Nissan models — most commonly on 240SX, 300ZX, 350Z. 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 Nissan range from $50 to $5,000, 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 Nissan by Model
Nissan 240SX(1 issue)
- Rear Main Seal and Valve Cover Oil Leaks1991-1998
The KA24DE engine in the 240SX is known for developing oil leaks from multiple locations as gaskets age. The rear main seal is the most problematic, leaking oil onto the clutch (manual trans) or flex plate (automatic). Valve cover gaskets also harden and leak, dripping oil onto the exhaust manifold. The oil pan gasket and front crank seal are additional common leak points. These leaks are exacerbated by age and the high operating temperatures of the KA24DE.
Nissan 300ZX(2 issues)
- Vacuum Hose Deterioration Causing Boost and Idle Problems (Twin Turbo)1990-1996
The Z32 Twin Turbo has over 100 vacuum hoses that deteriorate with age, causing a cascade of problems including boost leaks, erratic idle, failed boost transitions, and check engine lights. The rubber hoses become hard and brittle after 25+ years, cracking and splitting. The complex vacuum system controls boost, EGR, HVAC, and fuel pressure regulation. A single cracked hose can cause multiple symptoms.
- Twin Turbo Fuel System Degradation1990-1996
The Z32 300ZX Twin Turbo fuel system components degrade with age, causing significant reliability issues. The fuel injectors become clogged or develop poor spray patterns, fuel dampers can leak, and the rubber fuel lines become brittle and crack. The extremely tight engine bay makes fuel line inspection difficult, and leaking fuel near hot turbo components creates a serious fire risk. The factory fuel lines use rubber hoses with spring clamps that weaken over time. This is considered the most critical maintenance item on the Z32TT.
Nissan 350Z(1 issue)
- VQ35DE Rev-Up Engine Oil Consumption2005-2006
The revised VQ35DE "Rev-Up" engine (2005-2006 350Z, also known as the VQ35DE Rev-Up) is notorious for excessive oil consumption, often burning 1 quart every 1,000-2,000 miles. The issue is caused by defective galley gaskets (oil passage o-rings) that leak oil internally. The standard VQ35DE (2003-2004) and the later VQ35HR (2007-2009) do not suffer from this issue to the same degree. Nissan acknowledged the problem but did not issue a recall. The Rev-Up engine can be identified by its higher redline (7,000 vs 6,600 RPM).
Nissan Frontier(1 issue)
- Exhaust Manifold Stud Breakage and Manifold Leak Tick2000-2004
A common first-gen Frontier issue is broken exhaust manifold studs, especially on the VG33E/VG33ER V6. Heat cycling warps the manifold and stresses the studs until one or more snap, creating a ticking exhaust leak that is loudest on cold start. Owners often mistake it for valvetrain noise, but the sound usually fades somewhat as the manifold heats up and expands.
Nissan Maxima(1 issue)
- VQ35DE Excessive Oil Consumption2016-2023
The VQ35DE 3.5L V6 in the 2016-2023 Maxima can develop excessive oil consumption, burning 1 quart every 1,500-3,000 miles. The issue is more prevalent in higher-mileage examples and is caused by piston ring wear and PCV system issues. Low oil levels can damage the catalytic converters.
Nissan Murano(1 issue)
- Excessive Oil Consumption (VQ35DE Engine)2009-2014
The 2009-2014 Murano VQ35DE 3.5L V6 engine can consume excessive amounts of oil, sometimes 1 quart every 1,000-2,000 miles. The issue is caused by worn piston rings and valve stem seals. Nissan TSB NTB13-076 addresses the oil consumption test procedure. If the engine fails the consumption test, Nissan may authorize repairs under warranty.
Nissan Stanza(1 issue)
- Engine Oil Leaks (Multiple Locations)1990-1992
The KA24E engine in the Stanza develops oil leaks from the valve cover gasket, oil pan gasket, rear main seal, and front crank seal as the gasket materials age and harden. The most common and visible leak is from the valve cover gasket, which drips oil onto the exhaust manifold causing a burning oil smell. The rear main seal leak is more serious and labor-intensive to repair. These leaks are typical of aging KA24E engines across all Nissan applications.
Looking for P0174 on a different make?
View P0174 across all makes →Frequently Asked Questions
What does P0174 mean on Nissan?▼
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 Nissan specifically, this code is documented across 7 models.
What causes P0174 on Nissan vehicles?▼
Common causes on Nissan: 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 Nissan?▼
Repair costs on Nissan range from $50 to $5,000, depending on the specific model and root cause.
Which Nissan models have P0174 documented?▼
Au7o has documented P0174 on 7 Nissan models: 240SX, 300ZX, 350Z, Frontier, Maxima, Murano, Stanza.