P0459 OBD-II Trouble Code: Evaporative Emissions System Purge Control Valve Circuit High

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

SCHEDULE P0459 DIAGNOSTIC Get a fair and transparent estimate upfront
Red-stars EXCELLENT RATING ON

Cost of diagnosing the P0459 code

P0459 is a diagnostic trouble code (DTC) for "Evaporative Emissions System Purge Control Valve Circuit High". 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 for $69.99. 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$69.99$20.00
Toyota$69.99$20.00
BMW$69.99$20.00
SCHEDULE P0459 DIAGNOSTIC Get a fair and transparent estimate upfront

Check Engine Light

P0459 code definition

The P0459 code means that there has been a problem experienced with the vehicle’s evaporative (EVAP) system.

What the P0459 code means

If the P0459 code is set in the car’s computer, it means there has been a problem experienced within the evaporative system. This system includes a wide range of components, including the gas cap, the fuel filter, the system pressure sensor, flow sensor and many more. The car’s computer monitors fuel system pressure through a voltage reading. When that voltage is higher than expected, the system may turn on the Check Engine light.

What causes the P0459 code?

Potential causes for the P0459 code are varied, but they include the following:

  • Loose gas cap
  • Failed or damaged gasket on the gas cap
  • Damaged charcoal canister
  • Failed purge control solenoid
  • Damaged vacuum hoses
  • Damaged fuel vapor hoses
  • Faulty pressure sensor
  • Faulty flow sensor
  • Faulty PCM (rare)

What are the symptoms of the P0459 code?

The only symptom of a P0459 code is the Check Engine light turning on in the dash. This code should not result in drivability problems.

How does a mechanic diagnose the P0459 code?

The first step to diagnosing the P0459 code is connecting an OBD II scanner to the car’s computer and reading the codes stored there. It is likely there are several other evaporative system codes present. Next, the car should be test driven to see if the codes reset.

Following the test drive, the mechanic should begin with a visual and physical examination of the gas cap’s condition, including whether it is correctly installed and the condition of the gasket. If the problem is not related to the gas cap, the mechanic should inspect all vacuum lines for cracking or damage. The purge control solenoid should be tested (note that this may require the use of a vehicle lift and a smoke machine). A mechanic may also need to inspect all other evaporative system components, including the charcoal canister, fuel vapor hoses, pressure sensor, flow sensor and more. Note that solenoids should be removed from the vehicle before being tested.

Common mistakes when diagnosing the P0459 code

One of the most common mistakes seen when diagnosing the P0459 code is replacing parts without first performing a full diagnostic on the vacuum system. Loss of vacuum is the primary cause for the P0459 code to be set in the computer, and should be ruled out before any parts are replaced.

How serious is the P0459 code?

While the P0459 code will not result in drivability problems with your vehicle, it can lead to combustible fuel vapors being released into the atmosphere. This will also result in the car not being able to pass emissions testing. In a worst-case scenario, it can also have an adverse effect on fuel economy as the engine may not be able to burn fuel vapor correctly.

What repairs can fix the P0459 code?

The most common repair for the P0459 code is to inspect the fuel cap and reinstall it. Gas cap replacement is also common. However, in older vehicles, as well as those driven in areas where adverse conditions are common, vacuum line deterioration can be common. Other repairs include replacing damaged or failed solenoids, replacing the charcoal canister or a faulty sensor.

Additional comments for consideration regarding the P0459 code

While an incorrectly installed gas cap is one of the primary causes of the P0459 code, the vehicle should be thoroughly inspected to rule out any other potential causes, such as damaged vacuum or fuel vapor lines.

Need help with a P0459 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
P0459

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

SCHEDULE P0459 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

4.5/5

Number of Reviews

4,240

Rating Summary
3,884
174
45
26
111
3,884
174
45
26
111
Michael

Michael

18 years of experience
43 reviews
Michael
18 years of experience
Great.
1997 FORD EXPEDITION - CHECK ENGINE LIGHT IS ON - OLYMPIA, WASHINGTON
Robert

Robert

29 years of experience
179 reviews
Robert
29 years of experience
Fast, clean. Extremely good mechanic, from what I saw.
2012 HYUNDAI SONATA - CHECK ENGINE LIGHT IS ON - SAN JOSE, CALIFORNIA
Robert

Robert

18 years of experience
522 reviews
Robert
18 years of experience
Robert did a wonderful job taking the time to explain the issues that I was having with my car and what needed to be done.
2007 TOYOTA MATRIX - CHECK ENGINE LIGHT IS ON - WHEAT RIDGE, COLORADO
Jeffrey

Jeffrey

24 years of experience
683 reviews
Jeffrey
24 years of experience
Jeffery was on time and knocked out the required job in no time. He was very knowledgeable and trustworthy.
2011 HYUNDAI SONATA - CHECK ENGINE LIGHT IS ON - CHARLOTTE, NORTH CAROLINA

More related articles

Insurance Requirements for Car Registration in Kentucky
The Kentucky Transportation Cabinet requires that all drivers in Kentucky carry liability automotive insurance, or “financial responsibility” in order to operate a vehicle legally and maintain vehicle...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
Auto Safety Tips
Driving is more than a way to get from point A to point B. Owning and driving a car can also be a highly enjoyable experience. Whether a person is driving...

Related questions

Q: Throttle Position Sensor

Anytime you go to a parts store to get a computer scan for the Check Engine Light you are not getting a diagnosis of the problem but only a code retrieved from the engine control module (ECM) memory. This is...

Q: Car lost power

Hello. Most of the time when this car suddenly stops like this it is because the timing belt broke. If it has never been replaced then this is very likely. It can also occur if the ASD relay failed or...

Q: wont go faster 35mph

If the Check Engine Light is on this would be helpful as the codes that would be triggered by this would generate useful information relating to the problem. Without the benefit of hooking the car up to a scanner and...

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