P0191 on Mazda
Fuel Rail Pressure Sensor Circuit Range/Performance
P0191 on Mazda vehicles indicates fuel rail pressure sensor circuit range/performance. Au7o has documented this code across 1 Mazda model — most commonly on Mazda3. This code sets when the fuel rail pressure sensor's signal is out of its expected range or doesn't match what the computer expects for current conditions. On direct-injection and many modern engines, this sensor reports fuel pressure in the rail so the computer can precisely control fueling and the fuel pump. When the reading is implausible — too steady, erratic, or inconsistent with commanded pressure — this code is set, sometimes with hard starting, hesitation, or reduced power. It generally points to the sensor or its wiring, though an actual fuel-pressure problem can also trigger it.
Common Causes of P0191
- •Faulty fuel rail pressure sensor
- •Corroded, loose, or damaged sensor connector
- •Open, shorted, or high-resistance sensor wiring
- •Actual fuel pressure out of range (weak pump or regulator)
- •Restricted fuel filter or supply line
- •Loss of reference voltage or ground from the ECM/PCM
- •Faulty fuel pressure regulator or control valve
P0191 on Mazda by Model
Mazda Mazda3(1 issue)
- 2018 Mazda3 Denso Low-Pressure Fuel Pump Impeller Cracks - Engine Stall (Recall 21V875)2018
The in-tank low-pressure fuel pump supplied by Denso used an impeller molded with too low a density; it absorbs fuel, swells, cracks and deforms, then binds against the pump housing. Fuel delivery drops off, the engine runs lean, hesitates and can stall outright - sometimes at speed - and often will not restart when hot. This is the same defective Denso pump batch that hit millions of vehicles across several brands. Mazda's campaign covering 2018 Mazda3 and other models is NHTSA 21V875000, roughly 121,000 vehicles, with owner letters mailed July 2022. Owners report a long crank, a rough idle and low fuel rail pressure codes before the pump quits entirely.
Looking for P0191 on a different make?
View P0191 across all makes →Frequently Asked Questions
What does P0191 mean on Mazda?▼
P0191 stands for "Fuel Rail Pressure Sensor Circuit Range/Performance." This code sets when the fuel rail pressure sensor's signal is out of its expected range or doesn't match what the computer expects for current conditions. On direct-injection and many modern engines, this sensor reports fuel pressure in the rail so the computer can precisely control fueling and the fuel pump. When the reading is implausible — too steady, erratic, or inconsistent with commanded pressure — this code is set, sometimes with hard starting, hesitation, or reduced power. It generally points to the sensor or its wiring, though an actual fuel-pressure problem can also trigger it. On Mazda specifically, this code is documented across 1 model.
What causes P0191 on Mazda vehicles?▼
Common causes on Mazda: Faulty fuel rail pressure sensor, Corroded, loose, or damaged sensor connector, Open, shorted, or high-resistance sensor wiring, Actual fuel pressure out of range (weak pump or regulator), Restricted fuel filter or supply line. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0191 on a Mazda?▼
Repair costs vary widely depending on the root cause and specific Mazda model.
Which Mazda models have P0191 documented?▼
Au7o has documented P0191 on 1 Mazda model: Mazda3.