P0191 on your 2011 Dodge Ram 3500 points to a Fuel Rail Pressure Sensor Circuit Range/Performance issue. That means the PCM's not happy with the fuel pressure readings it's getting — either they're off compared to what it expects, or the sensor’s signal is erratic.
Here’s what could be going on:
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Faulty fuel rail pressure sensor (most common)
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Wiring issue — damaged harness or poor connection
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Weak fuel pump not delivering consistent pressure
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Clogged fuel filter causing pressure fluctuations
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Leaky injector or bad fuel pressure regulator
Fortunately, this manual does include diagnostics for this fault code, sensor testing procedures, and the wiring diagram for the fuel system if you want to dig in further.
