2001 Toyota Tundra 3.4L Extra Cab 4x4 P0440 EVAP System Fault - Solenoid Replacement & Diagnosis
Hello, I recently diagnosed a P0440 code on my 2001 Toyota Tundra 3.4L extra cab 4x4. I replaced one faulty solenoid in the EVAP system, and there are no visible leaks. I've also tested the other two solenoids: one responds correctly to commands via scan tool (can be turned on/off), while the second shows battery voltage but opens when grounded. Despite this, the P0440 code persists. Could anyone provide insight into potential causes or troubleshooting steps? The system appears intact, so I'm wondering if there could be an issue with the vapor pressure sensor, vacuum lines, or another component that might not be immediately obvious?
Circuit Description: The Vapor Pressure Sensor (VPS) and Vacuum Switching Valve (VSV) are used to monitor the EVAP system for abnormalities. DTC P0440 is set when a leak is detected in the EVAP system or if the vapor pressure sensor malfunctions. Possible causes include: 1. Damaged, disconnected, or restricted vacuum hoses or tubes. 2. Fuel tank cap loose or improperly installed. 3. Defective fuel tank cap (MOST OFTEN OVERLOOKED). 4. Damaged fuel tank. 5. Defective charcoal canister. 6. Open or shorted vapor pressure sensor circuit. 7. Faulty vapor pressure sensor. 8. Defective Engine Control Module (ECM).