Tracking Down P0455 on Your 2021 Ford Bronco
A P0455 on your 2021 Ford Bronco means the PCM found a large leak in the EVAP system—a breach equivalent to 0.040 inches or larger. Your 6th-generation Bronco with the 2.3L EcoBoost or 2.7L EcoBoost V6 is out of Ford's basic warranty but covered by the federal emissions warranty. The gas cap is your first suspect.
Evidence to Examine
- Check engine light with P0455
- Faint fuel odor, especially after off-road use
- Gas cap not seating properly
- Failed emissions inspection
Suspects Ranked by Likelihood
- Gas Cap Seal (Very High Likelihood): Worn or damaged seal—especially if you frequently remove the cap for off-road fueling. Replace for $10–$25.
- Canister Vent Solenoid (Medium Likelihood): Ford's vent solenoid exposed to trail debris near the charcoal canister. $120–$220.
- EVAP Vapor Lines (Medium Likelihood): Off-road vibration and flex can crack vapor hoses. $80–$200.
- EVAP Purge Valve (Low Likelihood): Stuck open or leaking. $100–$200.
- Charcoal Canister (Low Likelihood): Damage from water fording or overfilling fuel. $200–$350.
Diagnostic Steps
Replace the gas cap with an OEM Ford cap ($10–$25), clear the code, and drive 2–3 cycles. If P0455 returns, a Ford dealer will run IDS diagnostics and a smoke test. For Broncos used off-road, inspect the underside vapor lines and charcoal canister for trail damage.
Warranty Coverage
Ford's basic warranty (3 years/36,000 miles) has expired. The federal emissions warranty (8 years/80,000 miles) covers EVAP components through 2029. Contact your Ford dealer for mileage verification.
Safe to Drive?
Yes. P0455 doesn't affect the Bronco's engine, transmission, 4x4 system, or any off-road capability. Drive normally.