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

Our certified mechanics come to you · 12-month, 12,000-mile warranty

SCHEDULE P0451 DIAGNOSTIC 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
Check Engine Light
EVAP (Evaporative Emission Control) system

Fast and easy Check Engine Light is on Inspection service at your home or office.

SCHEDULE P0451 DIAGNOSTIC
Get a fair and transparent estimate upfront

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

4,743

Rating Summary
4,361
185
47
28
122
4,361
185
47
28
122

Oreste

12 years of experience
108 reviews
Oreste
12 years of experience
Nissan Altima - Check Engine Light is on - Hialeah, Florida
Showed up quick, and went straight to inspecting a brake light on the dash issue. He found the issue, fixed it, and showed me exactly what was wrong. Thank you!

Daniel

9 years of experience
58 reviews
Daniel
9 years of experience
Honda Fit - Check Engine Light is on - Chicago, Illinois
Told me everything I needed to know and switch out after the inspection. So, I scheduled another service the next day for all the fixes, or fluid maintenance.

Patrick

31 years of experience
1032 reviews
Patrick
31 years of experience
Hyundai Santa Fe - Check Engine Light is on - Austin, Texas
Even after working on my car, he took the time to explain what he did, the parts, and any next steps. Very knowledgeable!

Joe

12 years of experience
22 reviews
Joe
12 years of experience
Toyota 4Runner - Check Engine Light is on - Sacramento, California
Joe was very thorough in his inspections, and his knowledge & experience was clear in his explanations of what was wrong with my car. I really appreciated his recommendations, and the fact that he worked so efficiently that it cut down on time... I would definitely book with him again.

More related articles

How Long Does a Throttle Return Spring Last?
Not Not all vehicles on the road feature an electronic throttle control (ETC), which is also called drive-by-wire. For vehicles that don't offer this system, they have a throttle cable instead that is attached to the accelerator pedal, and runs...
How to Buy Fuel Treatments
Adding Adding a fuel additive to your gas tank when you fill up is one way to clean vital engine parts of deposits, improve the performance of your engine, and increase gas mileage. When trying to decide on which additive...
Veteran and Military Driver Laws and Benefits in New Mexico
The The state of New Mexico offers a number of benefits and perks for those Americans who have either served in an Armed Forces branch in the past, or are current active military members. Military honor plates New Mexico offers...

Related questions

I'm having problems with code po740

Hi there. In order to be able to give you more exact information I would need to know whether or not the vehicle is equipped with the CVT transmission. It sounds like you have the regular transmission in your vehicle....

2007 Chrysler 300 codes, Misfire, catalyst, evap, fuel, EGR, 02 sensor, 02 heater, comp, monitors, 1inc, 5 ready, p0457, p0456, th

When you have many different codes like this then you will need to have all of them tested and looked at to see if it is caused by one or more problems. If you have issues with vehicle after refueling...

My EVAP canister has a small leak

Hello! I suggest that a technician with a smoke machine test your EVAP system. The smoke will come out of any area of the EVAP system that is leaking. Most Auto shops will have a smoke machine. I would recommend...

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.

1-800-701-6230 · hi@yourmechanic.com