Tracking Down P0455 on Your 2021 Toyota Sienna
A P0455 on your 2021 Toyota Sienna indicates a large EVAP system leak. Your 4th-generation Sienna is hybrid-only—but it still has a 2.5L gasoline engine and complete EVAP system. The Sienna is out of basic warranty but covered by the federal emissions warranty. Gas cap first.
What You May Notice
- Check engine light with P0455
- Faint fuel odor
- Gas cap seal showing wear after 4–5 years
- Emissions inspection failure
Causes Ranked
- Gas Cap Seal (Very High Likelihood): Early seal wear. $10–$20 OEM replacement.
- Canister Close Valve (CCV) (Medium Likelihood): Vent valve sticking. $140–$240.
- EVAP Hose Crack (Medium Likelihood): Rubber vapor lines. $80–$220.
- Purge VSV (Low Likelihood): Vacuum switching valve. $100–$200.
- Fuel Sender Gasket (Low Likelihood): O-ring at fuel module. $100–$250.
What to Do
Replace the gas cap ($10–$20 OEM Toyota). Clear the code and drive 2–3 cycles. If P0455 returns, a smoke test will locate the leak.
Warranty Coverage
Toyota's basic warranty has expired. The federal emissions warranty (8yr/80k) covers EVAP through 2029. Contact your dealer.
Safe to Drive?
Yes. P0455 doesn't affect the Sienna's hybrid powertrain, AWD, power sliding doors, or any family features.