The P2420: Evaporative Emission System Switching Valve Control Circuit High refers to an issue where the evaporative emission system’s switching valve control circuit is receiving high voltage. This can affect the vehicle’s ability to manage fuel vapor emissions effectively, potentially leading to increased emissions and problems passing emissions tests.
P2420 – Quick Overview
Code | Information |
---|---|
Meaning | P2420: Evaporative Emission System Switching Valve Control Circuit High |
Is it serious? | Yes, high voltage in this circuit can lead to ineffective emission control and may cause the vehicle to fail emissions tests. |
Possible causes | – High voltage in the evaporative emission system switching valve control circuit – Faulty switching valve – Wiring or connector issues |
How to diagnose? | – Measure voltage in the switching valve control circuit – Inspect and test the switching valve and wiring – Check connectors for faults |
P2420 Meaning
The P2420: Evaporative Emission System Switching Valve Control Circuit High code indicates that the control circuit responsible for the switching valve in the vehicle’s evaporative emission system is experiencing higher than normal voltage. The switching valve directs fuel vapor flows within the emission system to control and reduce emissions effectively. High voltage in this circuit can prevent the valve from operating correctly, leading to increased emissions and potential environmental harm. Additionally, this issue can cause the vehicle to fail emissions inspections.
Step-by-step diagnostic guide
Action | Description | Tools Needed |
---|---|---|
Check for Other Codes | Use an OBD-II scanner to identify any additional related codes that might provide more context to the issue. Additional codes can help pinpoint the exact cause. | OBD-II Scanner |
Measure voltage in the switching valve control circuit | Use a multimeter to measure the voltage in the switching valve control circuit. Compare the readings to the manufacturer’s specifications to determine if the voltage is indeed high. | Multimeter, Wiring Diagram |
Inspect the Switching Valve | Visually inspect the evaporative emission system’s switching valve for any signs of physical damage, wear, or blockages. Ensure that the valve moves freely and is not stuck or obstructed. | Flashlight, Visual Inspection Tools |
Test the Switching Valve Operation | Use a diagnostic tool to activate the switching valve and observe its operation. Ensure that the valve responds correctly to control signals and operates as expected. Replace the valve if it does not function properly. | Diagnostic Tool, Replacement Switching Valve |
Inspect and Test the Switching Valve and Wiring | Perform a thorough inspection of the switching valve and its associated wiring. Check for any signs of fraying, corrosion, or damage that could affect the circuit’s performance. | Multimeter, Wire Repair Tools, Visual Inspection Tools |
Check Connectors for Faults | Inspect all connectors related to the switching valve control circuit for secure connections and signs of corrosion or damage. Clean or replace connectors as necessary to ensure a proper electrical connection. | Multimeter, Connector Cleaning Tools |
Replace Faulty Switching Valve if Necessary | If the switching valve is determined to be faulty after testing, remove and replace it with a new or properly functioning unit. Ensure that the replacement valve is compatible with the vehicle’s emission system. | Replacement Switching Valve, Basic Hand Tools |
Clear the Code and Test Drive | After performing the necessary repairs, clear the P2420 code using an OBD-II scanner. Take the vehicle for a test drive to ensure that the issue has been resolved and the code does not reappear. | OBD-II Scanner, Vehicle Owner’s Manual |
Recheck for Codes | After the test drive, use the OBD-II scanner again to verify that the P2420 code has been cleared. If the code returns, further diagnosis may be required to identify and fix underlying issues. | OBD-II Scanner |

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Hi, I am Juraj “Yuri” Lukacko. I got frustrated by unhelpful and scammy mechanics, so I decided to learn everything about car diagnostics myself. I test dozens of new car diagnostic tools every month along with learning new strategies to fix and customize cars. About Juraj Lukacko (Yuri)