Investigating P0455 on Your 2018 Nissan Altima
A P0455 on your 2018 Altima means the ECM detected a large EVAP leak. Your 5th-generation Altima (L33) with the 2.5L or 3.5L V6 is at the end of or past the federal emissions warranty. The gas cap is the #1 cause—and the cheapest fix.
Symptoms
- Check engine light with P0455
- Fuel odor near the rear
- Gas cap seal cracked after 7+ years
- Failed emissions inspection
Causes Ranked
- Gas Cap Seal (Very High Likelihood): Hardened or cracked after 7+ years. Replace for $10–$25.
- Vent Control Valve (High Likelihood): Common failure on older Nissan models. $120–$220.
- Purge Volume Control Valve (Medium Likelihood): PVCV stuck open. $100–$200.
- Vapor Line Deterioration (Medium Likelihood): Rubber hoses cracking with age. $80–$200.
- Charcoal Canister (Low Likelihood): Saturated from years of fuel overfilling. $200–$350.
Diagnostic Path
Replace the gas cap ($10–$25), clear the code, drive 2–3 cycles. If P0455 returns, a smoke test will find the leak. On the 5th-gen Altima, the vent control valve is a common and affordable DIY repair.
Warranty Coverage
Nissan's basic warranty has long expired. The federal emissions warranty (8yr/80k) expired in 2026. You're paying out of pocket, but most P0455 repairs are affordable.
DIY Feasibility
High. Gas cap is trivial. The vent control valve is near the charcoal canister under the rear—accessible with basic tools. The 5th-gen Altima is straightforward to work on.
Safe to Drive?
Yes. P0455 doesn't affect the Altima's engine, CVT, or driving systems.