2001 Ram 1500 5.2L Engine P0442 and P0455: How to Diagnose EVAP System Leak
My 2001 Ram 150-0 with a 5.2L engine is not staying running unless the foot is on the gas pedal. The check engine light is triggered by two diagnostic codes: P0442 and P0455, both related to evaporative emission control system leaks. I suspect a vacuum leak in the EVAP system, but I'm not sure where to start. What are the most common causes and how should I proceed with diagnosis?
A vacuum leak in the evaporative emission (EVAP) system is a likely cause of both P0442 and P0455. Start by using an EVAP system diagram to identify key components such as the charcoal canister, purge valve, and vent lines. A smoke machine is commonly used in professional diagnostics to detect leaks—this tool helps pinpoint where air is entering the system.