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2003 Mustang Cobra P1000 and P0446 OBD2 Codes: Evap System Fault Diagnosis

Model: 2003 mustang cobra Fault Code: P0446 Posted: 2015-05-06 12:23

I own a 2003 Mustang Cobra and recently scanned it with a handheld OBD2 scanner, which detected two fault codes: P1000 and P0446. The Check Engine Light is illuminated. The evaporative (EVAP) canister solenoid valve receives 12V when the ignition is on and grounds properly during operation. However, the solenoid does not shift as expected during EVAP system testing—no leak detected despite proper signal input. Additionally, the purge valve located under the passenger-side fender appears to be open continuously. I am receiving 12V to this valve, but no ground from the Powertrain Control Module (PCM) to close it. This suggests a potential issue with either the purge valve operation or the signaling circuit. Is there something I might have missed in my diagnosis? Any guidance on troubleshooting this EVAP system would be greatly appreciated.

Related fault codes
P0446P1000
Comments (3)
Anonymous 2015-05-12 21:52

Anyone else experiencing P0446 with a 2003 Mustang Cobra? The purge valve is normally closed (NC), and the PCM only grounds the circuit to close it when specific conditions are met. A scanner can command the valve open for testing, which helps verify functionality. Ensure that the signal wire isn or shorted to ground—this could cause erratic behavior. More details at: http://www.obd-codes.com/p0446

Anonymous 2015-05-13 07:57

The EVAP canister solenoid is open when the ignition is off, but closes properly when the engine is running and receives correct signals. I've inspected all EVAP hoses and found no visible damage or leaks. The issue appears to be with the purge valve on the passenger-side front fender. When energized using a power probe, it does not appear to open or close as expected. This suggests mechanical failure or faulty wiring. Should an EVAP purge valve operate in a typical on/off manner? Any insights would be helpful.

Anonymous 2015-05-13 09:19

The canister solenoid is open with ignition off. The sol is closing when car is running and is getting the correct signal. I checked all the evap hoses and they look good. It's the purge valve on passenger front fender that's acting weird. I don't believe it's opening & closing with the signal. I used my power probe and energized it with 12v and don't believe it's shifting. Should it open & close like any other valve? Thanks