P0443

P0443 is an electrical-circuit code, not a leak code — the ECU is reporting that the purge solenoid's control circuit is open, shorted, or otherwise outside the expected resistance/voltage range. This is the one EVAP code where smoke testing isn't the first move; the first move is a multimeter on the solenoid connector. Key-on, engine-off, you should see battery voltage on the power-side pin (the ECU supplies B+ to the solenoid and switches the ground); resistance across the solenoid itself should be in the 20-40 ohm range on most platforms. Common causes in order of frequency: corroded or backed-out connector pins at the purge solenoid (the connector sits in a hot, vibration-prone area), chafed wiring between the ECU and the solenoid, a failed solenoid coil (open winding), or rarely, a failed driver inside the ECU itself. The fuel cap is not the cause of P0443 — this is a wiring or component fault, full stop.

Vehicle-specific patterns: 2005-2015 Toyota/Lexus rarely throws P0443 unless a rodent has been chewing under the hood; when it does, it's usually a chafed wire where the harness passes a sharp bracket near the intake. 2003-2010 Ford 4.6L applications throw P0443 alongside P0441 fairly often because the same heat-cycling that cracks the purge valve diaphragm also degrades the connector pins and pigtail wiring; many shops replace the purge solenoid AND its pigtail as a matched repair on this platform. 2007-2014 GM full-size trucks see P0443 from connector corrosion when the truck has lived in road-salt states. 2008-2015 VW/Audi can throw P0443 on the N80 purge valve circuit, often after another repair that disturbed the harness routing. 2012+ Hyundai/Kia P0443 occurrences are most commonly bad connectors, sometimes a failed solenoid coil. Repair range: $0-20 for connector cleanup with dielectric grease, $80-200 for solenoid + harness pigtail, $400+ if internal ECU driver has failed.