2009 Hyundai Sonata P0449 Code: Voltage Reading and Solenoid Circuit Diagnosis
I own a 2009 Hyundai Sonata with a 2.4L engine and am currently experiencing a P0449 diagnostic trouble code. I have already replaced both the vent valve solenoid and the gas cap, but the issue persists. While the engine is running, I measured the voltage at the solenoid valve terminal: one terminal reads 12 volts (connected to battery positive), and the other reads 5 volts (connected to the ECM side). Is this reading normal? Could there be a wiring or sensor fault? Any guidance on how to properly diagnose this P0449 code would be greatly appreciated.
When the vent solenoid is disconnected, a 12V reading at the positive terminal (B+) is expected. However, the 5V reading on the ECM side of the circuit appears incorrect. Normally, there should be no voltage present on the ECM side when the solenoid is disconnected. You might consider comparing this to the purge solenoid circuit for reference. While BBBind.com provides a wiring schematic, it does not include specific reference voltages. This could help in identifying whether the issue lies in the circuit or the control module.