Tracking Down P0455 on Your 2021 Nissan Sentra
A P0455 on your 2021 Sentra means the ECM found a large EVAP leak. Your B18-generation Sentra with the 2.0L engine is out of Nissan's basic warranty but covered by the federal emissions warranty. The gas cap is the most common cause.
Evidence Present
- Check engine light with P0455
- Faint fuel odor near the rear
- Gas cap seal worn after 4+ years
- Failed emissions test
Causes Ranked
- Gas Cap Seal (Very High Likelihood): Worn rubber seal. 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 (Low Likelihood): Cracked hose. $80–$200.
- Charcoal Canister (Low Likelihood): Saturated from 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.
Warranty Coverage
Nissan's basic warranty (3yr/36k) has expired. The federal emissions warranty (8yr/80k) covers EVAP through 2029. Contact your dealer.
Safe to Drive?
Yes. P0455 doesn't affect the Sentra's 2.0L engine, CVT, or any systems.