451 code? What causes the P0451 code? How do I fix the error code P0451? If you drive a Ford F150 truck, you may encounter this error code. Well, it does not have something to do with your brakes, GPS, or locking differential.

However, it has something to do with your gas cap, gas tank, powertrain control module, and fuel pressure sensor? Want to learn more about the P0451 error code, its causes, what it means, and much more?

Let’s jump in!

What is P0451?

P0451 is an OBD2 fault code. It’s triggered when your Ford F150’s PCM detects an erratic voltage signal from the Emission Control system pressure sensor. This system helps prevent gasoline from escaping from the fuel system and fuel tank into the atmosphere.

Modern vehicles using gasoline could emit gasoline fumes from the engine and fuel tank if left unchecked. This would become a major source of hydrocarbon pollution. That means, the fuel system of gasoline vehicles would pollute the atmosphere 24 hours a day even when the engine is not running.

Thanks to the invention of the Emission Control System, vehicles cannot leak gasoline vapor into the atmosphere. The EVAP system has been a requirement in gasoline-powered vehicles since the 1970s. When this system detects pressure changes outside the accepted range, the sensors trigger the P0451 code.

What Does P0451 Mean?

As aforementioned, Ford vehicles have an Evaporative Emission Control Pressure system. This system has sensors and a reservoir. The reservoir captures any escaping gasoline vapors and sends them back to the F150 engine’s combustion.

If any gasoline vapor was to escape, the sensors would detect this and send data to the onboard computer. In turn, the computer will register this as a P0451 fault code. Basically, the computer will register that the PCM detected that fuel pressure is outside the manufacturer’s range.

How Serious is The P0451?

The P0451 code is a car manufacturer fault code found in vehicle models such as Toyota, Audi, GMC, Dodge, and Ford vehicles. The EVAP system in the Ford F150 has a reservoir called a canister. This reservoir collects excessive gas vapors while the engine is running. By doing so, it keeps gasoline vapors from escaping into the atmosphere.

While emission is a serious issue, the P0451 code is not. Basically, it should not cause your vehicle from running. However, if left ignored for a long period, not only will your Ford F150 cause lots of pollution. But the system’s pressure sensor will wear out.

When this happens, the check engine light will illuminate your dash and you’ll have to replace the sensor.

What Are the Causes of P0451?

The following are the causes of P0451.

Faulty Fuel Tank Pressure (FTP) Sensor

The fuel tank pressure sensor is commonly placed on the inside or top of the gas tank. Its function is to detect the pressure of the fuel system in gasoline-powered vehicles as well as enhance the vehicle’s fuel economy. It also detects evaporative leaks brought by a loose or faulty gas cap.

If the fuel tank pressure sensor is faulty, the amount of gas in your engine’s combustion chamber will decrease. This can cause your engine to stall, cause bad gas mileage, weak acceleration, and even hard starting.

Faulty Engine Control Module

The most common cause of the Engine Control module is one of the wiring harnesses. If the wires to the fuel injectors or the transmission corrode, they will lose their conductivity. As such, this will lead to the failure of the engine control module.

The engine control module performs a variety of functions necessary to ensure your vehicle runs smoothly. Also called the powertrain control module, it’s the brains of the engine management system. It works by controlling ignition timing, fuel mixture, emission control, and variable cam timing.

Loose Gas Cap

A loose gas cap will allow dirt and grime to find their way into the fuel system. Dirt and grime will contaminate the injectors causing more trouble. Not only that. It will allow fuel vapors to escape the fuel tank. If these vapors escape into the atmosphere, they will cause pollution.

When they also escape, the gas vapors produce an error code in the emission system which causes your check engine light to illuminate. To ensure the gas cap is not loose, remember to tighten it. Car manufacturers recommend tightening it until you hear it click three times.

What Are the P0451 Symptoms?

The following are symptoms of P0451.

Check Engine Light Will Illuminate

The check engine light will illuminate constantly or blink depending on the issue. If the check engine light illuminates an orange or red light, then it indicates that the issue needs immediate attention.

Something as simple as forgetting to tighten your gas cap can cause your check engine light to come on. This is because the gas cap helps to prevent gasoline vapors from escaping the fuel tank. If this were to happen, your fuel efficiency will reduce while your emissions increase.

Noticeable Fuel Odor

The fuel tank is where fuel sits as it waits to be pumped into the engine. If you fail to tighten the gas cap, it will begin to leak gas vapor. The smell of gasoline vapor in your F150 cabin is one of the symptoms that your gas cap is loose and leaking gas vapor.

A gas leak is a very serious issue. If the vapors come into contact with a heat source, they can cause an explosion. This will put you and your passengers in danger.

What Are the Solutions for P0451?

The following are solutions to P0451.

• Repair or replace a faulty fuel tank pressure sensor
• Tighten the fuel cap 
• Replace the fuel cap to ensure its tightness
• Replace damaged or defective wiring in the fuel tank sensor circuit
• Reprogram or replace the PCM
• Replace leaking or damaged hoses or lines
• Replace the canister if cracked, defective or broken

Frequently Asked Questions

1. Where is the EVAP pressure sensor located?

The EVAP pressure sensor is usually located on top of the fuel tank or inside the tank. As for the EVAP system, it reads pressure in the fuel system to detect gas leaks. It’s linked to the onboard computer of your vehicle.

2. How do I fix the error code P0451?

You can fix the error code P0451 by tightening the loose gas cap. Alternatively, you can visit your local mechanic and have the faulty fuel tank pressure sensor repaired or replaced.

3. How much does it cost to replace the fuel pressure sensor?

On average, expect to spend between $200 to $400 for a fuel pressure sensor replacement. Labor costs to replace the sensor will cost between $100 to $300.

4. Can I drive with a P0451 code?

Yes, you can still drive with a P0451 code, but we highly recommend having your vehicle checked by a professional. If gas vapors are leaking into the cabin of your F150, it could lead to serious injuries, especially if the vapors come into contact with a heat source.

Final Words

When it comes to the P0451 error code, never overlook it even though it does affect the performance of your Ford F150 truck. If your vehicle logs this error code, have a professional fix it. Do not wait until your next smog inspection. If you repair or replace the parts, you’ll save lives.