Fault code P0194 – fuel rail pressure sensor “A” circuit intermittent/erratic

Fault code P0194 is called “Fuel Rail Pressure (FRP) Sensor “A” Circuit Intermittent/Erratic” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.

Technical description and explained code P0194

This Diagnostic Trouble Code (DTC) is a generic powertrain code. Error P0194 is considered a generic code because it applies to all makes and models of vehicles. Although the specific repair steps may vary slightly from model to model.

Fault code P0194 – fuel rail pressure sensor

Some modern vehicles equipped with high pressure fuel injection systems have two fuel pumps. The low pressure pump (LP) is located in or near the fuel tank and the high pressure pump (HP) is located on the engine.

Typically, the low-pressure pump operates at 2.4-5.0 atmospheres. And the high pressure pump uses mechanical power, usually from the camshaft. So that once the pressure is increased, the fuel is fed to the direct injection injectors.

The ECM detects that the incoming signal from the fuel ramp pressure sensor is intermittent . This could be a mechanical failure or an electrical circuit malfunction, depending on the vehicle manufacturer, fuel type, and fuel system.

The MIL (Malfunction Indicator Light) will then illuminate and a DTC (Diagnostic Trouble Code) will be written into memory. Fault P0194 is defined as an intermittent “A” pressure sensor signal in the fuel rail.

Symptoms of vehicle malfunctions

The main signal that an error P0194 has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.

It can also be warning signs such as:

  1. Check engine control lamp on the control panel will light up (the code will be written to the ECM memory as a fault).
  2. The engine stalls or starts badly.
  3. Unstable engine operation when accelerating the vehicle.
  4. Bad acceleration of the vehicle.
  5. Loss of power.
  6. Increased fuel consumption.
  7. In some cases total failure of the engine.

The severity of the error P0194 is very high, the cause should be eliminated as soon as possible. Because when it appears, the car may have problems not only with drivability, but also complete engine failure.

Factors that can cause this error code

The error code P0194 can mean that one or more of the following problems have occurred:

  • A damaged fuel rail pressure sensor (FRP) is the most common cause.
  • Damaged connector or broken circuit to the sensor.
  • Excessive resistance in electric circuit.
  • High fuel pressure.
  • Low fuel pressure.
  • Vacuum leakage.
  • Low or no fuel level.
  • Sometimes faulty PCM module is the cause.

How to fix or reset OBD-2 code P0194

Some suggested steps for troubleshooting and fix the error code P0194:

  1. Read all stored data and error codes with an OBD-II scan tool.
  2. Clear the error codes from the computer memory.
  3. Test-drive the vehicle to see if error P0194 appears again.
  4. Visually inspect the connector and electrical wires for damage. If present, repair the damaged areas.
  5. Check the resistance to make sure it is within tolerance.
  6. Replace the faulty fuel rail pressure sensor (FRP).
  7. Test the engine control module (ECM).

Diagnose and repair of problems

Starting troubleshooting P0194, locate pressure sensor on fuel rail, once found, visually inspect connectors and wiring. Look for abrasions, exposed wires, burn marks, or melted plastic. Disconnect the connectors and carefully inspect the terminals inside. Inspect them for rust and other damage.

Remove diagnostic trouble code P0194 from the memory and see if it comes back. If it is gone, the problem was in the wires or connections. If the fault code returns, we will need to test the sensor and associated circuits.

Checking pressure sensor wiring

Using a digital voltmeter, check the 5V power supply signal circuit going to the sensor. Red wire to the 5 V supply circuit, black wire to ground. If 12 volts is present on the sensor, then as it should be 5, repair the wiring from the PCM to the sensor. This looks like a short or a faulty PCM.

If all is good on the signal circuit, make sure the ground on the FRP sensor is normal. Connect the test lamp to the plus side of the 12V battery and touch the other end of the test lamp to the FRP sensor ground.

If the indicator lamp does not light, this indicates a faulty circuit. If it lights up, jiggle the wiring harness going to the FRP sensor. To see if the check lamp blinks, this may indicate an intermittent connection.

When you do these tests, you will most likely find a problem with either the wiring or the sensor, which will need to be replaced. But if you still get a P0194 code after fixing it, that could indicate a PCM failure.

On which vehicles does this problem occur most frequently

Fault code P0194 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:

  • Ford (Focus, Kuga, Mondeo)
  • GMC
  • Lincoln (Town Car)
  • Renault (Megane)
  • Toyota (Corolla)
  • Volkswagen
  • Volvo

Fault code P0194 can sometimes be found with other errors. The most common are the following: P0102, P0174, P0183, P0351, P0352, P0353, P0354, P2106, P2195.


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