Chevrolet-specific code — factory diagnostic data| DTC Data Sheet | |
| Code | P0455 |
| Vehicle | Chevrolet Silverado 1500 (2007-2019) |
| Engine | all gasoline |
| System | EMISSION SYSTEM |
| Fault type | Leak |
| Official meaning | Evaporative Emission System Large Leak Detected |
Definition source: Chevrolet factory description. Diagnostic guidance is based on factory-defined fault logic for this code.
Decode any Chevrolet Silverado 1500 VIN — free recalls, specs & safety ratings — free VIN decoder with NHTSA data
Looking for the cross-vehicle definition? Read the generic P0455 article for the SAE-defined fault logic that applies to all manufacturers.
P0455 Quick Answer
P0455 on a Silverado 1500 means the EVAP system has detected a large leak — typically 0.040 inch or larger equivalent. The #1 cause is the gas cap (loose or worn seal), the #2 cause is a cracked EVAP hose at the canister or purge valve, and the #3 cause is the EVAP canister vent solenoid stuck open. Diagnose in that order — most P0455s are a $0 fix (tighten the cap).
What Does P0455 Mean on a Chevrolet Silverado 1500?
The Chevrolet Silverado 1500 (2007-2019) stores P0455 when the PCM detects the condition described above. This guide focuses on the all gasoline — the most common configuration on this platform. Diagnostic priorities and likely root causes differ from the generic SAE definition because of platform-specific failure patterns documented below.
Symptoms
- Check Engine Light (P0455) — no driveability symptoms
- Possibly a faint fuel smell near the rear of the truck after refueling
- Failure of OBD-II emissions inspection
- No effect on fuel economy or performance
Common Causes (Most Likely on This Model First)
The EVAP system is a sealed network that captures fuel vapor and routes it into the engine on cold-start. A “large leak” means the system can’t hold any vacuum. On the Silverado specifically:
- Loose or worn fuel cap. A cap that doesn’t seat properly or one with a hardened gasket fails the EVAP self-test. Tighten until you hear 3 clicks; if it tests bad, replace the cap ($15-$25).
- Cracked or disconnected EVAP hose. The plastic-quick-connect hoses near the EVAP canister (frame-mounted, under the bed forward of the rear axle) become brittle in cold climates and crack at the fittings. Inspect by hand — every quick-connect should feel firmly seated.
- Canister vent solenoid stuck open or contaminated. Located on the EVAP canister. Spider webs and road debris get into the vent — common on trucks driven on dirt roads. The solenoid won’t seal during the leak test.
- Cracked EVAP canister. The canister itself can crack at the seam after impact damage (rocks, etc.) since it’s exposed beneath the bed.
- Failing fuel tank pressure sensor. Reports incorrect tank pressure to the PCM, falsely triggering a leak code. Rare but possible.
Diagnostic Approach
- Tighten the fuel cap fully (3 clicks). Clear the code. Drive 50+ miles through a few warm-cold cycles. If the code doesn’t return, you’re done.
- If P0455 returns, inspect the fuel cap gasket. Worn or cracked rubber = replace the cap ($15-$25).
- Use a smoke machine connected to the EVAP service port (where present) or the canister vent. Look for smoke escaping anywhere along the lines from the gas tank to the engine.
- Inspect the EVAP canister and vent solenoid under the truck, forward of the rear axle. Disconnect the vent solenoid hose and check for debris in the fitting.
- Bidirectional scan tool: command the canister vent solenoid open and closed. With the engine off and vacuum pulled from the service port, watch tank pressure on live data — pressure should hold for at least 60 seconds with the vent closed.
- If smoke shows no leak and the vent solenoid commands and seats correctly, suspect the fuel tank pressure sensor.
Possible Fixes
| Fix | When |
|---|---|
| Tighten or replace fuel cap | Cap loose or seal hardened — start here, free or near-free fix |
| Replace EVAP hose / re-seat quick-connect | Smoke escapes from a hose joint |
| Replace canister vent solenoid | Debris in vent or solenoid sticks open under command |
| Replace EVAP canister | Smoke escapes from canister body — cracked or impact-damaged |
| Replace fuel tank pressure sensor | No leak found but tank pressure live-data reads incorrect |
Can I Still Drive With P0455?
Yes — P0455 has no effect on engine operation, mileage, or safety. The only impacts are the warning light, a failed OBD-II inspection if your state requires one, and (rarely) a fuel smell near the tank. You can defer the fix indefinitely from a mechanical standpoint, but inspection states will force the issue.
How Serious Is This Code?
Low. Cosmetic / regulatory only. The fix is usually trivial and cheap, so it’s worth addressing within a few weeks.
Repair Costs
| Repair | Estimated cost (parts + labor) |
|---|---|
| New fuel cap | $15 – $30 |
| EVAP hose / quick-connect repair | $40 – $180 |
| Canister vent solenoid | $80 – $180 |
| EVAP canister | $140 – $320 |
| Fuel tank pressure sensor | $140 – $280 |
| Diagnostic time (smoke test) | $80 – $140 |
FAQ
What is P0455 on a Chevy Silverado?
P0455 indicates a large leak in the evaporative emissions system. On a Silverado 1500 this is most often a loose or worn gas cap; secondary causes are a cracked EVAP hose, a stuck vent solenoid, or a cracked EVAP canister under the truck bed.
Will tightening the gas cap fix P0455 on my Silverado?
About 60-70% of the time, yes. Tighten the cap to 3 clicks, clear the code, and drive a few warm-cold cycles. If the code stays away, the cap was the cause. If it returns, you have a genuine leak somewhere in the EVAP plumbing.
How much does it cost to fix P0455 on a Silverado?
If it’s the cap: $15-$30. If it’s an EVAP hose: $40-$180. The canister vent solenoid is $80-$180. The most expensive fix — full canister replacement — runs $140-$320. Most Silverado P0455s resolve in the $0-$50 range.
Will P0455 affect my Silverado's fuel economy?
No. P0455 is a vapor-containment fault, not a fuel-delivery fault. Engine operation is unchanged and fuel economy is unaffected. The only consequence is the warning light and failing emissions inspection.