P0455 on GMC
Evaporative Emission Control System Leak Detected (Gross Leak)
P0455 on GMC vehicles indicates evaporative emission control system leak detected (gross leak). Au7o has documented this code across 1 GMC model — most commonly on Sierra 1500. This code means your car's evaporative emission (EVAP) system has detected a large (gross) leak, so fuel vapors that should be sealed inside the fuel and vapor system are escaping into the atmosphere. The EVAP system captures gasoline vapors from the tank and routes them to the engine to be burned instead of polluting the air, and the computer periodically pressure- or vacuum-tests this sealed system. A gross leak almost always points to something obvious and easy, like a loose, missing, or bad gas cap, rather than a deep mechanical failure. It rarely affects how the car drives, but it should be fixed to pass emissions and stop wasting fuel vapor. Typical repair costs on GMC range from $20 to $350, depending on the specific model and root cause.
Common Causes of P0455
- •Loose, missing, or improperly tightened gas cap
- •Worn, cracked, or failed gas cap seal
- •Cracked or disconnected EVAP/vapor hose
- •Damaged or missing fuel filler neck seal
- •Faulty EVAP purge valve stuck open
- •Failed EVAP vent valve
- •Cracked or damaged charcoal canister
P0455 on GMC by Model
GMC Sierra 1500(1 issue)
- P0455 — Gross EVAP Leak from Failed Vent Solenoid, Missing Gas Cap, or Broken Vent Hose2007-2023
P0455 indicates a large (gross) EVAP leak — the ECM cannot pull or hold vacuum in the evaporative system at all. On the Sierra 1500 the classic causes are a completely missing/unsealed gas cap, a stuck-open or failed EVAP vent solenoid (mounted under the truck near the fuel tank/spare tire, where it's exposed to road spray, dirt, and corrosion), and a cracked or disconnected vapor/vent hose. Because the vent solenoid sits at the canister under the bed, water intrusion and corrosion cause it to stick open, which the ECM reads as a wide-open system; a tell-tale symptom is the fuel nozzle repeatedly clicking off during refueling. The filler vent hose connector fracture noted in GM literature can also escalate to P0455. Symptom-wise the driver usually sees only the CEL, sometimes a fuel smell, and no performance loss.
Looking for P0455 on a different make?
View P0455 across all makes →Frequently Asked Questions
What does P0455 mean on GMC?▼
P0455 stands for "Evaporative Emission Control System Leak Detected (Gross Leak)." This code means your car's evaporative emission (EVAP) system has detected a large (gross) leak, so fuel vapors that should be sealed inside the fuel and vapor system are escaping into the atmosphere. The EVAP system captures gasoline vapors from the tank and routes them to the engine to be burned instead of polluting the air, and the computer periodically pressure- or vacuum-tests this sealed system. A gross leak almost always points to something obvious and easy, like a loose, missing, or bad gas cap, rather than a deep mechanical failure. It rarely affects how the car drives, but it should be fixed to pass emissions and stop wasting fuel vapor. On GMC specifically, this code is documented across 1 model.
What causes P0455 on GMC vehicles?▼
Common causes on GMC: Loose, missing, or improperly tightened gas cap, Worn, cracked, or failed gas cap seal, Cracked or disconnected EVAP/vapor hose, Damaged or missing fuel filler neck seal, Faulty EVAP purge valve stuck open. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0455 on a GMC?▼
Repair costs on GMC range from $20 to $350, depending on the specific model and root cause.
Which GMC models have P0455 documented?▼
Au7o has documented P0455 on 1 GMC model: Sierra 1500.