Fault code P018F – fuel system over pressure relief valve frequent activation

Fault code P018F is called “Fuel System Over Pressure Relief Valve Frequent Activation” 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 P018F

This Diagnostic Trouble Code (DTC) is a general powertrain code. Error P018F is considered a general 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 P018F – fuel system over pressure relief valve frequent activation

If your vehicle has retained code P018F, it means that the transmission control module (PCM) has detected a problem with the fuel pressure relief valve. In this case, it means that the PCM has noticed an excessively frequent actuation of the valve. This valve is designed to relieve fuel pressure if it is exceeded.

In most cases, the fuel pressure relief valve is actuated by a solenoid that is controlled by the computer. The valve is usually located on the fuel manifold or fuel line.

The PCM monitors the input signal from the fuel pressure sensor to determine if the valve needs to be actuated. When the fuel pressure is relieved, the excess is redirected back into the fuel tank through a designated return hose.

If fuel pressure exceeds the programmed limit, the PCM energizes the valve for a period of time long enough to initiate operation. To allow the fuel pressure to decrease to an acceptable degree.

If the PCM detects an unusual number of requested fuel pressure relief valve actuations within the programmed time period. Then code P018F will be stored and the Malfunction Indicator Light (MIL) may illuminate. In some cases, it may take several failure cycles for the MIL to illuminate.

Symptoms of vehicle malfunctions

The main signal that an error P018F has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.

It can also be warning signs such as:

  1. The “Check engine” control lamp on the control panel will illuminate (the code will be stored as a fault).
  2. Other related trouble codes may also be present, such as ignition misfire.
  3. Unstable engine operation, especially on cold starts.
  4. Rich exhaust, which may be a problem with the catalytic converter.
  5. Increased fuel consumption.

The severity of error P018F is high, the cause should be eliminated as soon as possible. As its occurrence indicates excessive fuel pressure, which can lead to serious mechanical damage.

Factors that can cause this error code

The error code P018F can mean that one or more of the following problems have occurred:

  • A faulty fuel pressure sensor is the most common cause.
  • Damaged connector or broken circuit to the sensor.
  • Excessive resistance in electric circuit.
  • Faulty electronic fuel pressure regulator.
  • Vacuum leakage in the fuel pressure regulator.
  • Sometimes the cause is faulty PCM module.

How to fix or reset OBD-2 code P018F

Some suggested steps for troubleshooting and fix the error code P018F:

  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 P018F appears again.
  4. Visually inspect the connector and electrical wires for damage. If any are found, repair the damaged areas.
  5. Check the resistance to make sure it is within tolerance.
  6. Replace the faulty pressure sensor.
  7. Test the power control module (PCM).

Diagnose and repair of problems

Locate the pressure sensor; once found, visually inspect the connectors and wiring. Look for scuffs, exposed wires, burn marks, or melted plastic. Disconnect the connectors and carefully inspect the terminals inside. Examine them for rust and other damage.

Remove diagnostic trouble code P018F 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 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 pressure sensor ground.

If the indicator light does not come on, this indicates a faulty circuit. If it lights up, jiggle the wiring harness. To see if the pilot light flashes, 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 have to be replaced. But if you still get a P018F code after fixing it, it could indicate a PCM failure.

On which vehicles does this problem occur most frequently

Fault code P018F can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:

  • Chevrolet
  • Dodge (RAM)
  • Ford
  • Honda
  • Toyota
  • GAZelle (Next)

Fault code P018F can sometimes be found with other errors. The most common are the following: P0190, P0191, P0192, P0193, P0194.


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