2000 Dodge Dakota P0442 Code: Evaporative Emission System Leak Diagnosis and Weather Patterns

Hi everyone, I'm experiencing the P0442 diagnostic trouble code on my 2000 Dodge Dakota, and I'd like to share my situation in hopes of getting some targeted advice. The issue first appeared during September/October 2005 — a period with unusually warm but damp weather in central New York. At that time, I took the truck to AutoZone for a scan, which detected a small evaporative (EVAP) system leak. They advised me to ensure my gas cap is always tightly secured and mentioned that if the code returned within 500 miles, they’d investigate further. The code reappeared just two days later — but unexpectedly went off by itself. It remained dormant until recently, when it came back on again after a warm, damp morning. I noticed a noticeable gasoline odor while starting the truck and leaving it running briefly to retrieve something from inside. After driving about 10 miles with the battery disconnected (ignition in 'run' for ~30 seconds), the check engine light did not come back. However, the next morning, the light returned and has stayed on ever since — now approximately three days later. After some research, I’ve identified a few potential causes: 1. Inspect the EVAP canister and associated hoses connected via the service port for cracks or damage. 2. Replace the gas cap with an OEM Dodge (Mopar) model. My main questions are: - Given that I smelled gasoline fumes, shouldn’t the system have triggered a more severe leak code (like P0453 or P0456)? The P0442 code is typically associated with small leaks. Is it possible for a minor leak to produce detectable odors? - Does warm and damp weather play a role in EVAP system performance? Could this environment cause increased vapor pressure, leading to more noticeable symptoms or triggering the sensor at specific times? I’ve already inspected all visible hoses — they appear intact and in good condition. The rubber and plastic components look brand new despite exposure to road conditions. One concern I have is the gas filler neck: it has a metal section that splits into two parts (one for fuel entry, one for venting), connected by rubber hoses leading into the tank. This metal portion appears heavily corroded. While I haven’t confirmed any pinholes visually, I’m concerned this could be an undetected leak point. I plan to first replace the gas cap with a genuine Mopar unit (purchased from Advance Auto Parts — Stant brand). It feels significantly tighter than the original and requires more force to achieve the three-click seal. I’ll monitor whether the P0442 code persists after this change. If that doesn’t resolve it, I may consider replacing the corroded filler neck section. I’d appreciate any insights on whether a small leak can produce strong odors or if weather conditions influence EVAP sensor sensitivity. Thanks for your help! — Bill