P2420 OBD-II Trouble Code: Evaporative Emission (EVAP) Switching Valve Control Circuit High

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Cost of diagnosing the P2420 code

P2420 is a diagnostic trouble code (DTC) for "Evaporative Emission (EVAP) Switching Valve Control 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. 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
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Toyota$20.00
BMW$20.00
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P2420 code definition

Evaporative Emission (EVAP) Switching Valve Control Circuit High

What the P2420 code means

The P2420 trouble code indicates that the Engine Control Module (ECM) has detected a malfunction within the switching control circuit of the EVAP control system of the engine. The EVAP system consists of multiple parts related to the intake, fuel, and exhaust of the engine. Many systems have a purge valve that opens and closes at certain times to vent fuel vapors from the fuel tank into the intake manifold.

What are the causes of the P2420 code?

  • A defective switching valve/purge valve
  • Cracked or broken fuel and vacuum lines
  • A clog in the EVAP system
  • A faulty Engine Control Module
  • A loose gas cap

What are the symptoms of the P2420 code?

Usually no symptoms other than an illuminated Check Engine Light are associated with the P2420 trouble code.

How does a mechanic diagnose the P2420 code?

  1. A mechanic may begin diagnosing the P2420 trouble code by first checking to make sure the gas cap is tightened securely.

  2. The mechanic would then pull up a diagram for the EVAP system of the vehicle in question.

  3. After that, the mechanic would locate all the parts of the EVAP system and begin inspecting them for visual damages.

These parts may include:

  • fuel lines
  • vacuum lines
  • the charcoal canister
  • the purge valve
  • any sensors involved in the EVAP system

Visual damages would include:

  • cracks
  • leaks
  • compromised wiring

If any of these issues are found, they would be relayed to the customer to make a repair decision.

Common mistakes when diagnosing the P2420 code

A common mistake that could be made when diagnosing the P2420 trouble code would be to replace the purge valve without being open minded to any other potential causes of the problem. It is important to be optimistic when it comes to diagnosing an automobile issue. The most likely cause is not always the answer.

How serious is the P2420 code?

Considering the fact that this code does not really have any symptoms associated with it, I would rank it low on the seriousness scale. Check Engine Lights bother most drivers so it is still a good idea to have the issue resolved as soon as possible, but this issue is by no means a life or death type situation.

What repairs can fix the P2420 code?

Additional comments regarding the P2420 code?

This code would be considered more serious if during the diagnosis the issue turns out to be fuel leak related. If this is the case, safety issues may be present as well as the risk of fire.

Need help with a P2420 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.

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P2420
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Michael

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Michael
17 years of experience
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Great experience with Michael! He expertly went over the car issues and provided information on all inspection points. Thank you!

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25 years of experience
GMC Envoy - Check Engine Light is on - Atlanta, Georgia
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23 years of experience
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23 years of experience
Saturn Ion - Check Engine Light is on - Washington, District of Columbia
Jermaine texted me to let me know that he was on his way. He was courteous and he arrived on time. Jermaine took the time to explain the problem I was having with my car and let me know that he would send a detailed report. I was more than happy with his service.

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Andrew
14 years of experience
Toyota Echo - Check Engine Light is on - Beaverton, Oregon
Andrew arrived early, and got right to work. He knew the likely problem from my 10 second description, checked the vehicle diagnostics, and verified the diagnostics by swapping some parts and doing a quick test drive. He even showed me the OBD2 scanner output. The vehicle has over 151k miles, and Androw could easily have tried to upsell me on replacing all of the ignition coils, rather than just the faulty one, purely based on the vehicle's age -- but he didn't. He just replaced the one necessary, topped up fluids, mentioned it was time for an oil change and new tires in the back, and that was it. Everything was fixed inside of an hour, while working in the rain.


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