Hey everyone, I've got a 2018 Ram 1500 Big Horn with the 5.7L Hemi. The check engine light came on last week. I hooked up my OBD-II scanner and it's showing a P0456 code, which points to a small EVAP system leak. I've checked the gas cap, tightened it, and even replaced it, but the light keeps coming back after a few drive cycles. The truck seems to run fine, no noticeable performance issues or strange smells. What should I be looking for next? Is this something I can tackle myself or should I head to the dealer?
2018 Ram 1500 Check Engine Light - P0456 Small EVAP Leak
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Melissa G. · rep 0 · May 22, 3:29 AM · 1 replies · solved · Question
✓ Accepted solution
ClearTheCode Admin
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ClearTheCode guidance (Ram · Diagnostics & codes)
Summary: For 2018 Ram 1500 Check Engine Light - P0456 Small EVAP Leak, work through these steps on your 2016+ vehicle:
- Confirm the symptom — note when it happens (cold start, highway, after fuel fill, etc.).
- Scan codes — save all pending/stored DTCs; don't clear until you've recorded them.
- Check TSBs & recalls — look up your VIN for open campaigns and known fixes.
- Inspect the obvious — related fuses, connectors, fluid level, and recent repairs.
- Test the common fix — follow model-specific service procedures; one change at a time.
- Escalate if needed — burning smell, no brakes, overheating, or stalling in traffic → shop visit.
Owner reported: Hey everyone, I've got a 2018 Ram 1500 Big Horn with the 5.7L Hemi. The check engine light came on last week. I hooked up my OBD-II scanner and it's showing a P0456 code, which points to a small EVAP system leak. I've checked the gas cap, tightened it, and even replaced it, but the light keeps coming back after a few drive cycles. The truck seems to run fine, no noticeable performance issues or st…
This is educational guidance, not a substitute for hands-on diagnosis.