OBD-II Generic Error Code P2420: How to Fix It

Q: Can I drive my car with a P2420 code?

Yes, in most cases you can continue driving with a P2420 code in the short term, as the EVAP system does not directly affect engine performance or safety. However, you may fail an emissions inspection, and leaving the underlying issue unresolved can eventually lead to fuel vapor leaks or damage to related components. It is best to diagnose and repair the issue as soon as possible.

Q: What is the most common cause of P2420?

The most common causes of P2420 are a failed or stuck EVAP switching valve solenoid, damaged or corroded wiring in the valve circuit, or a short to voltage in the signal wire between the PCM and the valve. In rarer cases, a faulty PCM or a saturated charcoal canister can also trigger this code.

Q: Will P2420 cause my check engine light to come on?

Yes, P2420 will illuminate your check engine light (also called the malfunction indicator lamp or MIL). The light will remain on until the fault is repaired and the code is cleared with an OBD2 scanner, or until the PCM completes enough drive cycles without detecting the fault again.

Q: How much does it cost to fix a P2420 code at a shop?

Repair costs vary depending on the root cause. Replacing the EVAP switching valve typically costs between $80 and $250 in parts and labor. Wiring repairs can range from $100 to $400 depending on the extent of damage. If the PCM needs reprogramming or replacement, costs can rise to $500 or more. Getting a diagnostic fee estimate upfront from your mechanic is always recommended.

Q: Can a bad gas cap cause a P2420 code?

A bad gas cap is more commonly associated with EVAP leak codes like P0457 or P0440 rather than P2420 specifically. However, it is still good practice to ensure your gas cap is tight and in good condition when diagnosing any EVAP-related code, as a loose cap can trigger multiple EVAP faults simultaneously.

Abstract

Error code P2420 indicates that your vehicle's powertrain control module (PCM) has detected an abnormally high voltage signal in the evaporative emission control (EVAP) switching valve circuit. This valve is responsible for controlling fuel vapors from the gas tank, preventing them from escaping into the atmosphere. A high circuit reading typically points to a wiring fault, a failed solenoid valve, or a PCM issue, and while the car may still drive, ignoring it can lead to failed emissions tests and potential fuel system damage.