Engine-CodesMercury – P0191 Mercury

P0191 Mercury Code - Fuel Rail Pressure Sensor Circuit Range/Performance

Quick Answer

The P0191 diagnostic trouble code (DTC) for Mercury vehicles indicates a problem with the Fuel Rail Pressure Sensor Circuit Range/Performance. Common causes include Faulty fuel rail pressure sensor, Wiring or connector issues in the sensor circuit, Clogged fuel filter restricting fuel flow. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means
P0191 Mercury indicates Fuel Rail Pressure Sensor Circuit Range/Performance.
Common causes
Common causes include Faulty fuel rail pressure sensor, Wiring or connector issues in the sensor circuit, Clogged fuel filter restricting fuel flow.
Severity
High - diagnose this code as soon as possible.
Can I drive?
Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Table of contents Created and updated by William Orellana on Sep 12, 2024
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Code P0191 Mercury Description

The P0191 diagnostic trouble code (DTC) for Mercury vehicles indicates a problem with the Fuel Rail Pressure Sensor Circuit Range/Performance. This code is triggered when the powertrain control module (PCM) detects that the signal from the fuel rail pressure sensor is outside the expected range or is not performing within the specified parameters. The fuel rail pressure sensor is a crucial component in the fuel system, as it monitors the pressure in the fuel rail and sends this information to the PCM, which uses it to adjust fuel delivery to the engine.

OBDII Code P0191 Mercury - Fuel Rail Pressure Sensor Circuit Range/Performance
P0191 Mercury Code - Fuel Rail Pressure Sensor Circuit Range/Performance

Common Causes of P0191 Mercury

  1. Faulty fuel rail pressure sensor
  2. Wiring or connector issues in the sensor circuit
  3. Clogged fuel filter restricting fuel flow
  4. Malfunctioning fuel pump affecting fuel pressure
  5. Problem with the fuel pressure regulator regulating fuel pressure

Symptoms of P0191 Mercury

  1. Check Engine Light illuminated on the dashboard
  2. Decreased fuel efficiency
  3. Rough idling or engine misfires
  4. Hesitation or lack of power during acceleration
  5. Engine stalling or difficulty starting

How to Fix P0191 Mercury

  1. Diagnose the issue by using a scan tool to retrieve the DTC and inspecting the fuel rail pressure sensor, wiring, and connectors for any visible damage.
  2. Test the fuel rail pressure sensor using a multimeter to check for proper voltage and resistance values.
  3. Inspect the fuel filter for clogs or restrictions and replace if necessary.
  4. Check the fuel pump and fuel pressure regulator for proper operation and replace if faulty.
  5. Clear the DTC and test drive the vehicle to ensure the issue has been resolved.

Cost to Fix P0191 Mercury

The cost of repairing a P0191 code on a Mercury vehicle can vary depending on the specific cause of the issue and the cost of parts and labor. On average, the repair for this code can range from $200 to $500, including parts and labor. However, it's important to note that diagnostic time and labor rates at auto repair shops can vary based on factors such as location, vehicle make and model, and engine type. It's recommended to check with local auto repair shops for a more accurate estimate based on your specific circumstances.

Tech Notes for P0191 Mercury









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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

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