OBD-II Trouble Codes

P0451 Code: Evaporative Emission System Pressure Sensor / Switch Range / Performance

Reading Time: 3 minutes

The EVAP Pressure Sensor, also known as a Fuel Tank Pressure (FTP) Sensor is a device that measures air pressure or vacuum in the evaporative emission (EVAP) system. This sensor is typically found on top of or inside of the fuel tank.

Fuel vapors are stored inside the EVAP canister. The PCM controls the purge control valve which opens to allow those vapors to be pulled into the engine and burned.

The role of the EVAP/Fuel Tank Pressure Sensor is to conduct pressure readings and convert this information into an electrical signal that is relayed to the Powertrain Control Module or PCM. Pressure or vacuum information is used by the PCM to monitor EVAP system purge flow. The PCM also uses the FTP signal when checking the EVAP system for leaks.

A trouble code is triggered when the FTP sensor signal falls outside the specified range for an extended period.

FTP sensor
Code P0451 is triggered if the FTP sensor signal falls outside the specified range for an extended period.

What Does the P0451 Code Mean?

The P0451 code is defined as Evaporative Emission Control System Pressure Sensor/Switch Range/Performance.

This diagnostic trouble code is set by the PCM when it detects that the Evaporative Pressure Sensor (also known as a Fuel Tank Pressure Sensor) indicates pressure change values that are not within the manufacturer-specified range. This could happen while an EVAP monitor test is being conducted and/or during the operation of a vehicle.

This code belongs to a range of related evaporative emission trouble codes which include P0450, P0452, P0453, P0454, P0455, P0456, P0457, P0458, and P0459.

Several Ford vehicles are prone to P0451 including the Ford F-150, Fusion, Mustang, and Focus. Aside from Ford, users have also reported P0451 in Chevrolet, Mercedes Benz, and Mazda vehicles.

What are the possible causes of the P0451 code?

Defective EVAP pressure sensor (fuel tank pressure sensor)

The P0451 code is considered one of the more straightforward trouble codes. This error code is typically set due to a faulty or failing EVAP/Fuel Tank Pressure Sensor.

Damaged wiring or poor connections in the EVAP/Fuel Tank Pressure Sensor circuit

Issues with the EVAP/Fuel Tank Pressure Sensor’s circuit can also trigger code P0451.

PCM failure

In rare cases, this trouble code may be erroneously set by a malfunctioning PCM in need of a software update.

illuminated check engine light of a car
P0451 code usually has no observable symptoms other than an illuminated Check Engine Light.

Symptoms of the P0451 code

Check Engine Light will illuminate

In most cases, there are no observable or adverse symptoms that accompany this
trouble code, other than an illuminated check engine light.

How to Diagnose the P0451 Code

To resolve the P0451 code, you need to determine its exact cause, which can prove challenging. If you are not confident with your DIY automotive repair skills, it’s best to leave the task to your mechanic. However, if you’re confident about your automotive knowledge, you can try researching diagnostic processes for your vehicle’s exact year, make, and model on forums to get an idea of what these might involve.

How to Fix the P051 Code

There’s no universal solution for code P051. The repair process will vary depending on the exact cause of the issue and the vehicle’s year, make, and model. It’s always best to bring your car to a mechanic if you’re unsure about diagnosis and repair.

If you think you have enough DIY experience to resolve the issue, it’s highly recommended that you still use online repair manuals to guide you through the repair process. You should also consider investing in an ALLDATA single-vehicle subscription, which should help you clear the P0451 code and give you more information on other repairs you may have to do on your car in the future.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic.

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