P2421 OBD-II Trouble Code: Evaporative Emission System Vent Valve Stuck Open

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

SCHEDULE P2421 DIAGNOSTIC Get a fair and transparent estimate upfront
Red-stars EXCELLENT RATING ON

Cost of diagnosing the P2421 code

P2421 is a diagnostic trouble code (DTC) for "Evaporative Emission System Vent Valve Stuck Open". 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 $70.00. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $30.00 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$70.00$30.00
Toyota$70.00$30.00
BMW$70.00$30.00
SCHEDULE P2421 DIAGNOSTIC Get a fair and transparent estimate upfront

Check Engine Light

P2421 Code Definition

The P2421 fault code indicates the vehicle’s on-board computer has detected either the vent valve or vent valve control circuit is stuck open in the evaporative (EVAP) control system, which recovers any raw fuel that may begin to evaporate within fuel storage.

What the P2421 code means

While the P2421 code registers, it indicates a change in fuel pressure due to the EVAP control system allowing raw fuel to evaporate.

What causes the P2421 code?

Several issues can cause the conditions triggering the P2421 code to register, ranging from a damaged or loose fuel cap to a faulty sensor. These conditions, however, are most frequently caused by a faulty vent valve or vent valve control solenoid.

What are the symptoms of the P2421 code?

Aside from the P2421 trouble code registering, it is not likely the vehicle will display any other symptoms, although other fault codes may also be present. Aside from the P2421 trouble code registering and setting the Check Engine Light, it is not likely the vehicle will display any other symptoms, although other fault codes may also be present.

How does a mechanic diagnose the P2421 code?

In diagnosing the P2421 OBD-II trouble code, a technician will first validate the presence of the code using a specialized scan tool. This tool retrieves data from the on-board computer and reports any anomalies in the form of trouble codes. Using personal experience and professional reference guides, the technician can narrow the potential causes of the P2421 code and perform a hands-on inspection (possibly using a smoke machine to help identify any leaks), repairing or replacing any parts deemed necessary before performing another scan to ensure the issue is resolved.

Common mistakes when diagnosing the P2421 code

After the P2421 trouble code registers, the most common mistakes in troubleshooting it are:

  • Failure to clear the P2421 trouble code after making repairs
  • Failure to validate the existence of the P2421 code
  • Not checking that the fuel cap is tight or testing for vacuum leaks before replacing EVAP control system components

How serious is the P2421 code?

While there are few - if any - symptoms to accompany the P2421 trouble code, neglecting to address the underlying issue can lead to greater problems down the road. It is, therefore, advisable to seek an inspection and make repairs promptly.

What repairs can fix the P2421 code?

After validating the existence of the P2421 fault code, the following repair(s) may be needed:

  • Repairing EVAP control system circuitry or connectors
  • Replacing the charcoal canister
  • Replacing the pressure or flow sensor
  • Replacing the purge control solenoid
  • Replacing the vent valve or vent valve control solenoid
  • Replacing vacuum or fuel vapor hoses
  • Tightening or replacing the fuel cap

Additional comments for consideration regarding the P2421 code

Often, the underlying issue causing the P2421 code to register is an intermittent one, which can make it difficult to diagnose. An intermittent condition may require extra time to troubleshoot due to the need for multiple tests. In some cases, it may even be necessary to allow the problem to worsen in order to identify the cause. If other trouble codes are present, it may be helpful for the mechanic in diagnosing the root cause of the P2421 code.

Need help with a P2421 code?

YourMechanic can connect you with a mobile technician capable to traveling to you to diagnose your P2421 fault code. Get a quote, book an appointment online, or speak with one of our service representatives at 1-800-701-6230.

trouble codes
Check Engine Light
P2421

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

SCHEDULE P2421 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

3,696

Rating Summary
3,372
162
42
24
96
3,372
162
42
24
96

Jerome

21 years of experience
246 reviews
Jerome
21 years of experience
Jerome was ahead of schedule which worked out great. He also went over other concerns with my car. Great service!
2008 TOYOTA CAMRY - CHECK ENGINE LIGHT IS ON - GLEN BURNIE, MARYLAND

Cameron

11 years of experience
67 reviews
Cameron
11 years of experience
My experience was great! He was very knowledgeable. He listen to my problems that I was having with my car.
2005 ACURA MDX - CHECK ENGINE LIGHT IS ON - AUBURN, WASHINGTON

Charles

14 years of experience
176 reviews
Charles
14 years of experience
Charles was excellent! Very professional and courteous! He did a great job!
2005 BMW 745LI - CHECK ENGINE LIGHT IS ON - WASHINGTON, DISTRICT OF COLUMBIA

Diego

18 years of experience
224 reviews
Diego
18 years of experience
Very professional and courteous
2015 FORD FOCUS - CHECK ENGINE LIGHT IS ON - BUCKEYE, ARIZONA

More related articles

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...
P0684 OBD-II Trouble Code: Glow Plug Control Module to PCM Communication Circuit Range/Performance
P0684 code means there is a failing connection within the Glow Plug Control Module often due too corroded wires and solenoid failures.
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.

Related questions

Q: Code P0303 cylinder 3 misfire

The symptoms you describe along with the blinking Check Engine Light and P0303 trouble code definitely tell us that you have a misfire in cylinder number 3. Your engine uses a coil on plug system. This means each individual...

Q: Misfire, loss of power, CEL comes on... Replacing ignition coils did not fix

Hello. The numbers you have provided did not yield any results through my search. If the part numbers are different, and the ends are physically different, then they may very well be different coils or it may just be an...

Q: Check Engine Light is on, trouble codes P0001 and P0006 are showing.

The fuel shut off valve is a solenoid that is controlled primarily by the shut off relay. The message you are receiving is telling you the circuit has low voltage. This means the solenoid is not energizing the way it...

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