AutoCodes – Mercury – P0194 Mercury

P0194 Mercury Code - Fuel Rail Pressure Sensor Circuit Intermittent

Quick Answer

The Fuel Rail Pressure (FRP) sensor is a diaphragm strain gauge device in which resistance changes with pressure. Common causes include High fuel pressure, Low fuel pressure, Damaged FRP sensor. 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: P0194 Mercury indicates Fuel Rail Pressure Sensor Circuit Intermittent.
Common causes: Common causes include High fuel pressure, Low fuel pressure, Damaged FRP sensor.
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.

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Code Popularity 337

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Feb 10, 2021

Description
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code P0194 Mercury Description

The Fuel Rail Pressure (FRP) sensor is a diaphragm strain gauge device in which resistance changes with pressure. The electrical resistance of a strain gauge increases as pressure increases, and the resistance decreases as the pressure decreases. The varying resistance affects the voltage drop across the sensor terminals and provides electrical signal to the Powertrain Control Module (PCM) corresponding to pressure.
Strain gauge type sensors are consider passive sensors. A passive sensor is connected to a voltage divider network so that varying the resistance of the passive sensor causes a variation in total current flow.
Voltage that is dropped across a fixed resistor in series with the sensor resistor determines the voltage signal at the PCM. This voltage signal is equal to the reference voltage minus the voltage drop across the fixed resistor.
The FRP sensor measures the pressure of the fuel near the fuel injectors. This signal is used by the PCM to adjust the fuel injector pulse width and meter fuel to each combustion cylinder.

OBDII Code P0194 Mercury - Fuel Rail Pressure Sensor Circuit Intermittent - AutoCodes.com — P0194 Mercury Code - Fuel Rail Pressure Sensor Circuit Intermittent

What does this mean?

What are the Possible Causes of the DTC P0194 Mercury?

High fuel pressure
Low fuel pressure
Damaged FRP sensor
Excessive resistance in the circuit
Low or no fuel
Wiring harness connector of the fuel pressure sensor
Fuel Rail Pressure Sensor
Fuel

How to Fix the DTC P0194 Mercury?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0194 Mercury code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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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.