Investigating P0455 on Your 2020 Chevrolet Suburban
A P0455 on your 2020 Suburban means the ECM detected a large EVAP leak. Your 11th-generation K2XX Suburban with the 5.3L or 6.2L V8 is out of GM's basic warranty but covered by the federal emissions warranty. The gas cap is the most common cause.
Symptoms
- Check engine light with P0455
- Possible P0449 companion code
- Faint fuel odor near the rear
- Gas cap seal worn after 5+ years
- Failed emissions inspection
Causes Ranked
- Gas Cap Seal (Very High Likelihood): Worn rubber seal. Replace for $10–$25.
- Vent Valve Solenoid (Medium Likelihood): Common K2XX GM failure. $100–$200.
- Purge Solenoid (Medium Likelihood): Stuck open. $80–$180.
- Vapor Line (Low Likelihood): Cracked hose under the large body. $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 with P0449, the vent valve solenoid is the cause. Easy to access on the Suburban.
Warranty Coverage
GM's basic warranty (3yr/36k) has expired. The federal emissions warranty (8yr/80k) covers EVAP through 2028.
Safe to Drive?
Yes. P0455 doesn't affect the Suburban's V8, 6-speed automatic, 4x4, or towing capacity.