What does code P0455 versus P0442 mean for EVAP leaks?

Code P0455 indicates a large leak in the EVAP system while code P0442 indicates a small leak, and both relate to fuel vapors escaping from the evaporative emission control system. The difference is mainly the size of the leak the computer detected. For both codes, the first and cheapest thing to check is the gas cap, since a loose or worn cap is the most common cause. If the cap is fine, the leak may be a cracked hose, a faulty purge or vent valve, or a damaged charcoal canister. A smoke test is the most reliable way to locate either size of leak. At Motoro Cars in Miami, our ASE-certified, AAA-approved technicians use computerized diagnostics and smoke testing to find EVAP leaks precisely. Call Wynwood at (786) 634-2002 or Doral at (786) 633-3220 to get your EVAP code diagnosed and sealed.