P018F Frequent activation of the overpressure relief valve in the fuel system

P018F Frequent activation of the overpressure relief valve in the fuel system

OBD-II DTC Datasheet

Frequent operation of the overpressure safety valve in the fuel system

What does this mean?

This is a generic transmission diagnostic trouble code (DTC) applicable to OBD-II vehicles. This may include, but is not limited to, Dodge, Toyota, Ford, Honda, Chevrolet, Dodge, Ram, etc. Despite the general nature, the exact repair steps may vary depending on the model year, make, model and transmission configuration. ...

If your vehicle has stored a code P018F, it means that the powertrain control module (PCM) has detected a problem with the fuel pressure relief valve.

In this case, it means that the PCM has noticed an overly active fuel pressure relief 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 controlled by the PCM. The valve is usually located on the fuel rail or in the fuel supply line. The PCM monitors the input from the fuel pressure sensor to determine if the fuel pressure relief valve is required to operate. When the fuel pressure is released, excess fuel is redirected back to the fuel tank through a specially designed return hose. When the fuel pressure exceeds the programmed limit, the PCM applies voltage and / or ground to the valve long enough to start operation and allows the fuel pressure to drop to an acceptable level.

If the PCM detects an unusual number of requested fuel pressure relief valve actuations within a set period of time, a P018F code will be stored and a malfunction indicator lamp (MIL) may illuminate. Some applications may require multiple ignition cycles (with failure) for the MIL to illuminate.

What is the severity of this DTC?

Since excessive fuel pressure is a contributing factor to the storage of the P018F code, and since excessive fuel pressure can cause serious mechanical damage, this code should be considered serious.

What are some of the symptoms of the code?

Symptoms of a P018F trouble code may include:

• Rich exhaust conditions
• Rough idle; especially with a cold start
• Reduced fuel efficiency
• Engine misfire codes due to dirty spark plugs

What are some of the common causes for the code?

Reasons for this P018F transfer code may include:

• Defective fuel pressure sensor
• Defective fuel pressure regulator
• Insufficient vacuum in the fuel pressure regulator
• Open or short circuit in the fuel pressure sensor circuit or electronic fuel pressure regulator
• Defective PCM or PCM programming error

What are some steps to troubleshoot the P018F?

Before diagnosing the P018F code, you will need access to a diagnostic scanner, digital volt / ohmmeter (DVOM), manual fuel gauge (with appropriate fittings and accessories), and a reliable source of vehicle information.

After a thorough visual inspection of the system wiring and connectors, check all vacuum lines and system hoses for cracks or deterioration. Repair or replace wiring and vacuum hoses as necessary.

Find the car diagnostic port and connect the scanner to get all stored codes and freeze frame data. You can help your upcoming diagnosis by writing down this information and putting it aside for later. This is especially true if the code is intermittent. Now clear the codes and test drive the vehicle to see if it resets immediately.

If the code is flushed immediately:

Step 1

Check the fuel pressure to determine if it is excessive. If there is no evidence that this is the case, suspect a faulty fuel pressure sensor (or a faulty PCM) and go to step 3. If the fuel pressure is excessive, go to step 2.

Step 2

Use the DVOM and vehicle information source to check the electronic fuel pressure regulator (if applicable). If the electronic fuel pressure regulator does not meet manufacturer's specifications, replace it and test drive the vehicle to see if the problem has been corrected.

If the vehicle is equipped with a mechanical (vacuum operated) fuel pressure regulator, make sure that it has a constant vacuum supply (engine running) and that no fuel is leaking from the inside. If the fuel pressure is too high and there is sufficient vacuum in the regulator, you may suspect that the vacuum regulator is defective. If the regulator internally leaks fuel, consider it faulty and replace it. Test drive the vehicle until the PCM enters ready mode or P018F is cleared.

Step 3

Use the DVOM and specifications obtained from your vehicle information source to check the fuel pressure regulator as recommended by the manufacturer. Replace the regulator if it does not meet the requirements. If sensor and regulator are within specifications, go to step 4.

Step 4

Disconnect all related controllers from related circuits and use the DVOM to test resistance and continuity on individual circuits. Repair or replace chains that are not in accordance with the manufacturer's recommendations. If all components and circuits are in good working order, suspect that the PCM is defective or that there is a programming error.

• Use caution when checking high pressure fuel systems.
• A defective fuel pressure relief valve will not set the P018F code.

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