2001 Ram 1500 5.2L Engine Codes P0442 and P0455 - Evap System Leak After Smoke Test
My 2001 Ram 1500 with a 5.2L engine is showing diagnostic trouble codes P0442 and P0455. A smoke test identified an evaporative emissions system leak. I performed multiple evap system tests after repairs, and they passed each time. However, the codes persist during driving. What could be causing this issue despite passing the initial tests?
Both P0442 and P0455 indicate evaporative system leaks—wiring or mechanical issues are unlikely to be the root cause. The only other known solution beyond standard smoke testing is TSB 25-04-01, which suggests checking the purge valve for proper seating; a faulty or misaligned valve can prevent correct operation and lead to recurring codes.