P0193 OBD-II: Fuel Rail Pressure Sensor "A" Circuit High

What Does P0193 Code Mean?

OBD-II Code P0193 is defined as a Fuel Rail Pressure Sensor Circuit High Input

The Powertrain Control Module (PCM) needs to know the fuel pressure at all times so it can effectively control the fuel injectors and deliver the optimal amount of fuel into the engine's combustion chambers for maximum power and economy while maintaining the lowest tailpipe emissions.

Code P0193

indicates that the signal from the Fuel Rail Pressure Sensor and/or its circuit is too high, indicating a fuel pressure condition that is abnormally high.

P0193 Symptoms

• Check Engine Light will illuminate
• Fuel Consumption may be higher than normal
• Tail pipe emissions may smell unusual
• Engine hesitation or stalling
• Engine may die/stall at stop signs
• Fuel trim codes (P0172 fuel system to rich) may be triggered
• Vehicle fails emissions test
• In rare cases, no abnormal symptoms may be noticed

Common Problems That Trigger the P0193 Code

• Defective Fuel Rail Pressure Sensor
• Defective Fuel Rail Pressure Sensor Circuit or connector
• Damaged/Defective Fuel pressure regulator

Common Misdiagnoses

• Fuel Rail Pressure Sensor is replaced when the cause is a defective Fuel Pressure Regulator
• Fuel Rail pressure Sensor is replaced when the cause is a defective fuel pump
• Fuel Rail Pressure Sensor is replaced when the cause is a poor connection or chafed wiring

P0193 Diagnostic Theory for Shops and Technicians

First thing to do is to gather the Freeze Frame Data in order to analyze the engine's operating conditions when the code was set. Then, test drive the vehicle with a quality data streaming scan tool and watch the fuel pressure PID. Do the fuel pressure readings go too high? If so, test the actual fuel pressure with a mechanical fuel pressure gauge to see if the sensor and/or its circuit is at fault or, if there is a fuel pressure problem. If the fuel pressure is normal, then test the Fuel Rail Pressure Sensor connector and wiring with a labscope to verify the circuitry is intact. If the circuitry is intact, and the 'real' fuel pressure is normal, then the Sensor is most likely at fault. If the fuel pressure is abnormally high, then inspect the fuel delivery system in order to determine the cause of the high fuel pressure.