What Does P0446 Mean?
The PCM has detected a malfunction in the EVAP vent control circuit. The vent valve (also called the canister close valve) is responsible for sealing the EVAP system during leak tests. When this circuit fails, the PCM cannot properly test the EVAP system for leaks. The driver will see a check engine light and the vehicle will fail emissions testing.
Common Causes
35%
Failed EVAP vent valve/solenoid (stuck open or stuck closed)
25%
Open or shorted wiring in the vent valve circuit
20%
Blocked or restricted vent valve filter (dirt, spider webs, debris)
15%
Corroded or loose electrical connector at the vent solenoid
5%
PCM vent valve driver circuit failure
Diagnostic Steps
1
Locate the EVAP vent valve (typically near the charcoal canister under the vehicle or near the fuel tank). Disconnect the connector and measure solenoid resistance: should be 20-50 ohms depending on manufacturer.
2
With the vent valve connector disconnected, use a multimeter to check harness continuity from the PCM connector to the vent valve connector. Verify both signal and ground wires are intact with less than 2 ohms resistance.
3
Check for shorts to ground and shorts to power on both harness wires with the connectors at both ends disconnected.
4
Apply 12V directly to the vent valve solenoid terminals and listen/feel for an audible click indicating the valve is actuating. No click means a failed solenoid.
5
Inspect the vent valve filter screen for blockage from dirt, insect nests, or debris. Clean or replace if restricted.
6
Using live data, command the vent valve on/off via the scan tool bidirectional controls while monitoring the fuel tank pressure sensor for appropriate response.
Estimated Repair Cost
$100 - $400
Parts + labor, varies by vehicle and location
The PCM has detected a malfunction in the EVAP vent control circuit. The vent valve (also called the canister close valve) is responsible for sealing the EVAP system during leak tests. When this circuit fails, the PCM cannot properly test the EVAP system for leaks. The driver will see a check engine...
The most common cause of P0446 (Evaporative Emission Control System Purge Control Valve Circuit Shorted) is: Failed EVAP vent valve/solenoid (stuck open or stuck closed)
Typical repair costs for P0446 range from $100 to $400, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to drive. This code relates to emissions system integrity testing and does not affect vehicle drivability or safety. Repair is needed to pass emissions inspections.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0446 to identify the root cause.
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Quick Info
Category
Powertrain
System
EVAP / Emissions System
Difficulty
Type
Generic (SAE)
Recommended Tools
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