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P2421 Severity
Once the vehicle's onboard system no longer detects the issue, most codes will disappear on their own. If your vehicle still has this code, however, it should be properly diagnosed to avoid a more serious problem.
For a proper diagnosis, RepairPal Certified shops have the equipment, tools, and expertise.
Moderate severity codes might not threaten the vehicle's safety or functionality immediately, but you should still get it diagnosed within a reasonable time frame to keep your car running well.
The evaporative control (EVAP) system captures any fuel vapors from the fuel tank and sends them through the vehicle's intake to be burned in the normal combustion process. The EVAP Vent Valve allows fresh air to enter the EVAP system so it is not under a constant vacuum. When the engine control module (PCM) detects the evap system is venting when it should not, it will set code P2421.
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OBD-II Code Powertrain Control Module (PCM) failure is defined as a Evaporative Emission System Vent Valve Stuck Open
The evaporative control (EVAP) system captures any fuel vapors from the fuel tank and sends them through the vehicle's intake to be burned in the normal combustion process. The EVAP Vent Valve allows fresh air to enter the EVAP system so it is not under a constant vacuum. When the engine control module (PCM) detects the evap system is venting when it should not, it will set code P2421.