P0172 on Nissan
System Too Rich (Bank 1)
P0172 on Nissan vehicles indicates system too rich (bank 1). Au7o has documented this code across 2 Nissan models — most commonly on Pathfinder, Rogue. P0172 means the engine computer has determined the air/fuel mixture on bank 1 is too rich — there is too much fuel relative to air. The PCM watches the oxygen sensors and fuel trims; when it must repeatedly cut back fuel to compensate for an over-rich condition and hits its correction limit, it sets this code. Bank 1 is the side of the engine containing cylinder number one. You may notice poor fuel economy, rough idle, a sulfur/rotten-egg smell, black exhaust smoke, or fouled spark plugs. Typical repair costs on Nissan range from $60 to $1,200, depending on the specific model and root cause.
Common Causes of P0172
- •Dirty or faulty mass airflow (MAF) sensor
- •Leaking or stuck fuel injector
- •High fuel pressure (faulty regulator)
- •Faulty oxygen sensor giving skewed readings
- •Clogged or dirty air filter
- •Leaking evaporative purge valve adding fuel vapor
- •Engine coolant temperature sensor reading too cold
- •Worn spark plugs causing inefficient combustion
P0172 on Nissan by Model
Nissan Pathfinder(1 issue)
- Fuel pressure damper / regulator leak causing fuel smell and hard starting1996-1999
On the VG33E (1996+), the fuel-rail pressure damper and the fuel pressure regulator use internal diaphragms that fail with age. A ruptured diaphragm lets raw fuel weep from the damper or get drawn through the regulator vacuum line into the intake, producing a strong fuel smell, hard/long cranking hot restarts, and misfire or rich running. A simple test: run the engine a few minutes, shut off, and pull the vacuum line off the regulator/damper; fuel in the line confirms a failed diaphragm.
Nissan Rogue(1 issue)
- 1.5L VC-Turbo Engine Oil Smell, Rough Running, and Check Engine Light from PCV / Crankcase Ventilation Faults2022-2025
On 2022+ Rogues equipped with the 1.5L KR15DDT variable-compression turbo engine, owners have reported rough idle, oil odor, hesitation, and check-engine lights tied to crankcase ventilation or related air-fuel control issues. These complaints are distinct from outright transmission concerns and appear in owner forums and complaint databases as the newer engine accumulated mileage. In some cases, the issue presents as drivability problems without obvious external leaks.
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View P0172 across all makes →Frequently Asked Questions
What does P0172 mean on Nissan?▼
P0172 stands for "System Too Rich (Bank 1)." P0172 means the engine computer has determined the air/fuel mixture on bank 1 is too rich — there is too much fuel relative to air. The PCM watches the oxygen sensors and fuel trims; when it must repeatedly cut back fuel to compensate for an over-rich condition and hits its correction limit, it sets this code. Bank 1 is the side of the engine containing cylinder number one. You may notice poor fuel economy, rough idle, a sulfur/rotten-egg smell, black exhaust smoke, or fouled spark plugs. On Nissan specifically, this code is documented across 2 models.
What causes P0172 on Nissan vehicles?▼
Common causes on Nissan: Dirty or faulty mass airflow (MAF) sensor, Leaking or stuck fuel injector, High fuel pressure (faulty regulator), Faulty oxygen sensor giving skewed readings, Clogged or dirty air filter. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0172 on a Nissan?▼
Repair costs on Nissan range from $60 to $1,200, depending on the specific model and root cause.
Which Nissan models have P0172 documented?▼
Au7o has documented P0172 on 2 Nissan models: Pathfinder, Rogue.