Solving P0455 on Your 2020 Nissan Altima
A P0455 on your 2020 Altima means the ECM detected a large EVAP leak. Your 6th-generation Altima with the 2.5L engine is out of Nissan's basic warranty but covered by the federal emissions warranty. The gas cap is the prime suspect.
Symptoms
- Check engine light with P0455
- Faint fuel odor near the rear
- Gas cap seal worn after 5+ years
- Failed emissions inspection
Causes by Probability
- Gas Cap Seal (Very High Likelihood): Worn after 5+ years. Replace for $10–$25.
- Vent Control Valve (Medium Likelihood): Nissan's vent valve sticking. $120–$220.
- Purge Volume Control Valve (Medium Likelihood): PVCV stuck open. $100–$200.
- Vapor Line Crack (Low Likelihood): Deteriorating rubber hose. $80–$200.
- Charcoal Canister (Low Likelihood): Saturated from overfilling. $200–$350.
Diagnostic Path
Replace the gas cap with an OEM Nissan cap ($10–$25), clear the code, drive 2–3 cycles. If P0455 returns, a smoke test will locate the leak. The vent control valve is near the charcoal canister under the rear.
Warranty Coverage
Nissan's basic warranty (3yr/36k) has expired. The federal emissions warranty (8yr/80k) covers EVAP through 2028. Contact your dealer.
Safe to Drive?
Yes. P0455 doesn't affect the Altima's engine, CVT, or driving systems.