Evaporative Emission Control System Leak Detected (Large Leak)
The P0455 code means the vehicle's onboard diagnostic system has detected: Evaporative Emission Control System Leak Detected (Large Leak). This is a moderate severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- medium
- Estimated cost
- $5-$30 for gas cap; $80-$200 for vent valve; $200-$500 for filler neck
A cracked or loose gas cap causes 60%+ of EVAP codes. This $8 replacement clears P0442, P0455, and P0457 more often than any other repair.
If a new gas cap does not clear it, the leak is somewhere in the EVAP plumbing. A smoke machine finds the exact leak -- a cracked hose, bad seal, or stuck vent valve -- in minutes instead of guessing at parts.
Clear the code after the repair. If the light stays off after 50 miles, you just saved $200+ in shop fees.
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Common Symptoms
- Check Engine Light on
- Strong fuel odor near the vehicle
- Possible emissions test failure
Probable Causes (Ranked by Likelihood)
- Missing or severely damaged gas cap Very High
- Disconnected or broken large EVAP hose High
- Failed or stuck-open vent valve High
- Cracked or split fuel filler neck Moderate
- Damaged charcoal canister Moderate
Common Fixes by Vehicle
What techs usually find when diagnosing P0455 on specific vehicles — tap your vehicle for the fix and the exact part:
2004-2017 Toyota Tacoma/4Runner easy (cap) DIY
Loose or damaged gas cap is the most common cause. If the cap is tight and code returns, check the EVAP charcoal canister under the truck -- road debris damages it. Also check the vapor pressure sensor on the fuel tank. Your dealer can confirm whether an open service bulletin or warranty extension applies to your VIN.
Labor: 5 min (cap), 1 hour (canister)2007-2018 Jeep Wrangler JK 3.6L/3.8L easy DIY
EVAP purge valve failure is extremely common. Located on the intake manifold, easily accessible. Mopar. Also check the gas cap seal -- Wranglers get a lot of dust/dirt that degrades the cap seal faster. After any off-roading, inspect EVAP lines under the body for damage. Confirm the exact part for your year and engine with a retailer's fitment lookup or your VIN before ordering - these applications split by engine and build date.
Labor: 20 min2009-2020 Chevrolet Silverado/Sierra 5.3L easy DIY
Check the EVAP vent solenoid mounted near the charcoal canister behind the rear axle. The solenoid sticks open, causing a large leak detection. ACDelco is the OE replacement. Also inspect the EVAP line from the tank to the canister for rust-through. Your dealer can confirm whether an open service bulletin or warranty extension applies to your VIN. Confirm the exact part for your year and engine with a retailer's fitment lookup or your VIN before ordering - these applications split by engine and build date.
Labor: 30 min2008-2019 Nissan Rogue/Pathfinder 2.5L moderate DIY
The EVAP leak detection pump (mounted near the charcoal canister) fails on Nissan vehicles around 80-100K miles. The pump motor burns out and cannot pressurize the system for self-test. Dorman is the aftermarket replacement. Access is under the vehicle near the fuel tank. Confirm the exact part for your year and engine with a retailer's fitment lookup or your VIN before ordering - these applications split by engine and build date.
Labor: 1 hourFrequently Asked Questions
What is the difference between P0442 and P0455?
P0442 is the small-leak code and maps to the 0.040 inch monitor that CARB's OBD II regulation requires (Title 13 CCR 1968.2, section (e)(4.2.2)(B)); P0456 maps to the tighter 0.020 inch monitor. P0455 is the gross-leak code — the regulation does not define an orifice size for it, so how big a leak sets P0455 is manufacturer-specific rather than a fixed 0.080 inch figure. A large leak is often as simple as a missing gas cap.
Is P0455 an emissions or safety issue?
Primarily emissions. The larger concern is the fuel odor, which represents raw hydrocarbon vapors. These are flammable and should be addressed promptly, especially near heat sources.
Mechanics Guide Step-by-step diagnosis
Step-by-Step Diagnostic Procedure
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Verify the gas cap is present and properly seated with an undamaged seal.
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Visually trace all large EVAP hoses (3/8 in or larger) from the fuel tank to the charcoal canister and to the engine.
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Command the vent valve closed with a scan tool and monitor fuel tank pressure: pressure should hold if the system seals.
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Perform a smoke test with the vent blocked to locate the large leak. A large leak will be immediately visible.
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Inspect the filler neck where it attaches to the fuel tank for cracks or loose clamps.
Sources 3
This page is built from documented references. Verify against your own service info before repair work.
- California Code of Regulations, Title 13 section 1968.2 (OBD II)malfunction criteria, section (e)(4.2.2)
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
- Cross-checked against the SAE J2012:2002 DTC table (2026-08-27)archived scan of the SAE standard — readable copy, not SAE’s current edition
P0455 on Diesel, EV & Equipment
The same code ID appears across other engines and platforms. The diagnostic flow varies by manufacturer — these are the platform-specific breakdowns:
Commonly Affected Vehicles
- Chevrolet Silverado and GMC Sierra
- Ford F-150 and Expedition
- Dodge Ram 1500
- Toyota Tundra and Sequoia
- Jeep Grand Cherokee
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