P0451 OBD-II Trouble Code: Evaporative Emission Control System Pressure Sensor Range/Performance

Our certified mechanics come to you · Get a fair and transparent estimate upfront

Red-stars EXCELLENT RATING ON

Cost of diagnosing the P0451 code

P0451 is a diagnostic trouble code (DTC) for "Evaporative Emission Control System Pressure Sensor Range/Performance". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

Cars Estimate Credit towards follow-up repair Earliest Availability
Ford$20.00
Toyota$20.00
BMW$20.00
SCHEDULE P0451 DIAGNOSTIC Get a fair and transparent estimate upfront

Diagnostic Trouble Code (DTC): P0451

P0451 code definition

When the PCM (powertrain control module) detects an incorrect, erratic, or otherwise improper voltage signal from the evaporative emission control system pressure sensor, a P0451 code is set and the Check Engine Light illuminates.

What the P0451 code means

As fuel is stored in the vehicle’s fuel storage system, some of it will evaporate over time. As this happens, the evaporative emission control system captures that evaporated fuel and then systematically purges it into the engine’s combustion process. When the P0451 code is set, it shows that the evaporative pressure sensor has detected pressure changes that are outside the accepted manufacturer specifications for the vehicle.

What causes the P0451 code?

A few different problems may cause the P0451 code to be stored. These include:

  • A defect in, or damage to, the gas tank
  • A problem with the fuel tank sending unit
  • A faulty fuel tank pressure sensor
  • An open or shorted fuel tank pressure sensor circuit
  • A faulty canister vent valve (somewhat rare)
  • A faulty PCM (rare)

What are the symptoms of the P0451 code?

In almost all cases, the only symptom will be the illumination of the Check Engine Light. In some cases, however, you may notice the smell of gasoline coming from your vehicle’s engine. In most instances, other codes related to the evaporative emission control system will begin to appear as well.

How does a mechanic diagnose the P0451 code?

Using an OBD-II scanner, the mechanic will identify the codes that have been saved by the PCM. They’ll then begin addressing each code in the order in which it was stored. In most cases, when a P0451 code is stored, other related codes will be stored after it, so the P0451 code should be resolved first.

The first thing to look for in this case, after identifying the code(s), will be damaged, corroded, chafed, or otherwise faulty wiring, connectors, and circuits. After repairing any instances of these, the mechanic will clear the code(s) and retest the system. Then they will move on inspect the charcoal canister, the purge valve, the vacuum and vapor hoses, and all other components related to the evaporative emission control system. With each inspection and repair, they will clear the codes and retest the engine until the problem is resolved.

Common mistakes when diagnosing the P0451 code

The most common mistake associated with a P0451 code is failing to properly inspect all components, wiring, and connectors before replacing any part of the evaporative emission control system. For example, in some cases, a vacuum leak could be due to a loose or damaged fuel cap, not a faulty vacuum hose.

What repairs can fix the P0451 code?

In some instances, the repair for a P0451 code could be as simple as replacing the gas cap. Most of the time, though, resolving the issue will involve one or more of the following repairs:

  • Repairing or replacing the gas tank.
  • Repairing or replacing a faulty fuel tank pressure sensor.
  • Replacing defective or damaged wiring or connectors in the fuel tank pressure sensor circuit.
  • Replacing the canister vent valve.
  • Replacing or reprogramming the PCM (rare).

Additional comments for consideration regarding the P0451 code

Because it usually has no discernible symptoms, other than the Check Engine Light illuminating, some vehicle owners assume that a P0451 code is not a serious issue and that it doesn’t need to be resolved until the vehicle is due for an OBD-II emissions test. However, this issue can result in significantly lower fuel efficiency, and it can trigger other problems, as well. Thus, it’s important to resolve it before it costs you more time and money later on.

Furthermore, if a more extensive repair is needed to resolve the code, it’s a good idea to address these sooner rather than later, especially when you need to resolve the code in order to pass an emissions test and renew your vehicle’s registration.

Need help with a P0451 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

trouble codes
EVAP (Evaporative Emission Control) system
Check Engine Light

No more waiting rooms! Our mechanics will come to you to diagnose and fix the P0451 code.

SCHEDULE P0451 DIAGNOSTIC
Get a $20 credit for the follow-up repair

Recent Check Engine Light is on Inspection reviews

Excellent Rating


YourMechanic Check Engine Light is on Inspection Service

Average Rating

4.8/5

Number of Reviews

5,170

Rating Summary
4,765
197
50
27
131
4,765
197
50
27
131

Fred

16 years of experience
364 reviews
Fred
16 years of experience
Mercedes-Benz E500 - Check Engine Light is on - Conroe, Texas
Fred was very friendly and thorough to get to the root of the issue. Even when he could not find a fault to why my engine light was on, he went above and beyond to make absolutely sure that the concern was minimized. Turns out, all that needed to be done was a reset but his diagnostic to address my issues was very intricate and appreciated.

David

17 years of experience
37 reviews
David
17 years of experience
Chevrolet Cruze - Check Engine Light is on - Aurora, Colorado
David was on time, professionalisms & honest! I would definitely request him again and pass along to friends/family.

John

18 years of experience
18 reviews
John
18 years of experience
Dodge Ram 1500 - Check Engine Light is on - Memphis, Tennessee
Demonstrated good integrity. Advised me when work I thought needed done was unnecessary and was helpful in identifying issues that needed to be addressed

Robert

21 years of experience
17 reviews
Robert
21 years of experience
Chrysler 200 - Check Engine Light is on - Fort Worth, Texas
Robert did a good job working on my car and letting me know what's needed to keep my car driving smoothly.


More related articles

Related questions

I'm getting a check engine light with codes p0455 and p0456. I tried a new gas cap from the dealer but the light comes back in a few days.

Hi there. The fuel cap could have been one item that may have been leaking. There could be a leaking return fuel vapor line or the purge vent valve could be damaged. Check the fuel system and look for any...

P2107 - 2005 Ford Freestyle

Hello. P2107 is the code for an issue with the vehicle's throttle control module processor. Basically, the computer has detected an issue with the vehicle's electronic throttle body and has put the vehicle in safe mode. The throttle body...

Does the throttle position sensor and thermostat need to be changed before I take a three hour trip?

The code for the thermostat is due to the engine coolant is not getting up to operating temperature quick enough and is due to a stuck open thermostat most likely. The TPS code may be an intermittent issue with sensor...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1 (855) 347-2779 · hi@yourmechanic.com