2002 Oldsmobile Alero P0446 and P0453 Error Codes: Causes and Solutions
I have a 2002 Oldsmobile Alero. After replacing the fuel pump and gas cap about a month ago, two diagnostic trouble codes appeared: P0446 and P0453. I cleared the codes, but they returned after two weeks. There is no noticeable gas odor, and I experience dizziness when driving with windows closed—possibly related to vacuum system issues or fuel level at half tank. Could this be a faulty EVAP vent valve or sensor malfunction?
The P0446 and P0453 codes are most likely linked to the fuel pump replacement or an issue with the EVAP system's vent valve. The FTP (fuel tank pressure) sensor operates at high voltage, so any electrical or vacuum-related faults can trigger these codes. Additionally, EVAP system tests do not run continuously; they require specific conditions such as engine temperature and fuel level to initiate, which may explain why the codes appear intermittently after a reset.