What is the code P0455 on a Chevy Volt?
The P0455 code signals a gross evaporative emissions system leak in Chevy Volt models. In plain terms, the car’s on-board computer detected a large leak in the EVAP system that can trigger the check engine light.
In more detail, P0455 is part of the standardized OBD-II code set. The Volt’s EVAP system captures fuel vapors from the tank and routes them to a charcoal canister for later combustion. A gross leak can originate from a loose gas cap, cracked hoses, a faulty purge or vent valve, or a damaged canister. Because the system is sealed, even a relatively small crack can fail the test, and a leak large enough to register as P0455 typically requires diagnostic repair to restore proper emissions control and fuel economy.
What P0455 means for the Volt
The code indicates a large leak in the evaporative emissions control system was detected. The Volt’s EVAP system is designed to prevent fuel vapors from escaping to the atmosphere by storing them in a charcoal canister and then purging them into the engine. A gross leak can come from components such as the fuel cap, EVAP hoses, purge/vent valves, or the canister itself. Driving with this code may affect emissions performance and fuel efficiency, and the check engine light may stay on until the issue is repaired.
Common causes and checks
Common causes of P0455 in a Chevy Volt typically involve the EVAP hardware or seals. The following items are the most frequently found culprits.
- Loose, missing, or faulty gas cap
- Cracked, split, or disconnected EVAP hoses or fittings
- Faulty purge valve (solenoid) or vent valve
- Damaged or degraded charcoal canister
- Leak on the fuel tank or filler neck due to corrosion or damage
- Wiring or connector issues to EVAP sensors/solenoids
In many cases, the problem starts with a simple gas cap issue. If the cap is not sealing properly, tightening or replacing it can clear the code. If the leak persists after addressing the cap, further inspection is required to locate a more substantial leak in the EVAP system.
Diagnosis and repair steps
The following approach is commonly used to diagnose and repair P0455 on a Chevy Volt. The list provides a logical sequence from initial check to confirmation of repair.
- Verify the code with a scan tool and check for related or pending codes.
- Inspect the gas cap for proper seating, wear, or damage; replace with a correct part if needed.
- Visually inspect EVAP hoses, connections, and the filler neck for cracks, disconnections, or deterioration.
- Perform a smoke test of the EVAP system to reveal leaks that aren’t obvious by sight or touch.
- Test purge and vent valves for proper operation (electrical control, vacuum integrity, and seals).
- Inspect the charcoal canister for cracks, saturation, or damage; replace if warranted.
- Clear codes and perform a drive cycle to verify the repair; recheck with a scan tool if the code returns.
Note: Some diagnostics require specialized tools and procedures. If you’re not experienced with EVAP testing, it’s advisable to have a qualified technician perform the work to avoid misdiagnosis or further leaks.
What to expect in terms of repairs and costs
Repair costs for a P0455 in a Chevy Volt vary widely based on what component is causing the gross leak. The following ranges give a rough idea, but actual prices depend on the model year, location, and labor rates.
- Gas cap replacement: approximately $10–$50 (parts and minimal labor)
- EVAP hose/titting replacement: roughly $20–$150 for parts plus 1–2 hours of labor
- Purge or vent valve replacement: about $60–$250 for parts and labor
- Charcoal canister replacement: typically $250–$700 or more, including labor
- Smoke test and diagnostic labor: variable, often required if the cause isn’t obvious
Costs can be higher if multiple components are damaged or if the repair requires access adjustments around the fuel system or under the vehicle. Some EVAP repairs may be covered under warranty or recalls, depending on the vehicle’s age and service history. Always obtain an itemized quote before authorizing repairs.
Summary
In short, P0455 on a Chevy Volt signals a gross leak in the evaporative emissions control system. The usual first step is to check the gas cap, followed by a thorough inspection of EVAP hoses, valves, and the canister. If the leak persists, a diagnostic smoke test helps pinpoint the source, after which the necessary component(s) can be repaired or replaced. Timely handling helps protect emissions performance, fuel economy, and overall vehicle reliability.
