P0455: EVAP System Leak Detected - Large Leak
What Does P0455 Mean?
P0455 is a diagnostic trouble code indicating: EVAP System Leak Detected - Large Leak. This code relates to the emission controls system. It has been reported in NHTSA complaints across 23 different vehicle models.
The Evaporative Emission Control (EVAP) system captures fuel vapors from the gas tank and routes them to the engine to be burned instead of released into the atmosphere. The system consists of a charcoal canister (absorbs vapors), purge valve (opens to route vapors to the engine), vent valve (allows air into the system), and a network of hoses. The ECU periodically tests the system for leaks by sealing it and monitoring pressure changes. A leak as small as 0.020 inches can trigger a code.
The EVAP (Evaporative Emission Control) system captures fuel vapors from the gas tank and routes them to the engine to be burned. Without it, gasoline vapor (primarily volatile organic compounds/VOCs) would escape into the atmosphere, contributing to ground-level ozone formation (smog). The system consists of: charcoal canister (absorbs and stores vapors), purge valve (opens to route stored vapors to the engine intake), vent valve (allows fresh air into the system for purging), hoses connecting all components, and the gas cap (seals the system). The ECU tests the system for leaks by sealing it and monitoring pressure changes using a fuel tank pressure sensor. EVAP codes are among the most common OBD-II codes and are almost never dangerous — they don't affect engine performance at all. However, they will keep the check engine light on and fail emissions testing. Common affected vehicles: GM trucks (vent valve solenoid is a known weak point — $25-$80 part), Toyota (purge valve failures), Honda (canister clogging from topping off fuel tank), Ford (vapor line cracking from age and heat).
**Real-World Diagnostic Walkthrough:** P0455 indicates a large EVAP leak, which is actually easier to find than a small leak because the leak source is more substantial. Check in this order: (1) Gas cap — tighten or replace. (2) Look under the vehicle for disconnected EVAP hoses — a hose knocked loose by road debris is a common cause. (3) Check the charcoal canister for cracks (usually near the rear of the vehicle). (4) Check the purge valve solenoid — a stuck-open purge valve creates a large opening in the EVAP system (located on or near the intake manifold). (5) If nothing is visually obvious, a smoke test will reveal the leak quickly since it's large enough to produce visible smoke flow. On older vehicles, check for rust-through in the fuel filler neck — the corrugated metal neck between the gas cap and tank can develop holes.
Symptoms of P0455
- ⚠️ check engine light
- ⚠️ noticeable fuel smell
- ⚠️ failed emissions test
- ⚠️ no drivability issues typically
Common Causes
- 🔍 Missing or severely damaged gas cap
- 🔍 Disconnected or cracked EVAP hose
- 🔍 Cracked charcoal canister
- 🔍 Stuck-open purge or vent valve
- 🔍 Damaged fuel filler neck
P0455 Reports by Year
Real Owner Reports
From NHTSA complaint database — actual owner descriptions.
"CHECK ENGINE LIGHT CAME ON AND THE PERFORMANCE OF THE VEHICLE IS BAD. BAD IDLE, WEAK ENGINE, JUST THE CAR IS NOT PERFORMING PROPERLY. I USED THE SCANNER TO SEE THE CODE AND I HAD MORE THAN ONE . P0171 P0505 P117B P0441 P0455 . FUEL/AIR MIXTURE IS LEAN . AND I HEAR THE FUEL PUMP MAKING THAT NOISE THA"
— Toyota Camry owner, 06/20/2020
"ONGOING ISSUES WITH MY FUEL SYSTEM. CAR WILL DISPLAY ONE OF THESE MANY SYMPTOMS: -MISFIRE, HARD START, STALL OR SHUTOFF. OTHER SYMPTOMS INCLUDE CAR STUTTERING AND STALLING OUT WHILE DRIVING. THIS LAST SYMPTOM IS VERY DANGEROUS AS IT OFTEN COMES WITH NO WARNING. WHEN THE CAR STALLS OUT, THE CAR IS D"
— Toyota Rav4 owner, 05/22/2020
"My 2011 Honda CR-V's Check Engine Light came on within the past week, and continues to stay on. I went to Autozone to get a diagnostic check. Per their recommendations, I tightened the fuel tank cap but the check engine light is still on. It also diagnosed a P0455 EVAP, Emission Control System Leak "
— Honda Cr-V owner, 10/07/2022
Source: NHTSA Complaints Database
Most Reported Vehicles for P0455
Based on NHTSA owner complaint data.
| # | Vehicle | Reports |
|---|---|---|
| 1 | FORD FUSION | |
| 2 | FORD ESCAPE | |
| 3 | HYUNDAI SONATA | |
| 4 | KIA SOUL | |
| 5 | DODGE DURANGO | |
| 6 | TOYOTA CAMRY | |
| 7 | TOYOTA RAV4 | |
| 8 | HONDA CIVIC | |
| 9 | HONDA CR-V | |
| 10 | FORD EXPLORER | |
| 11 | CHEVROLET SILVERADO | |
| 12 | CHEVROLET EQUINOX | |
| 13 | CHEVROLET TRAVERSE | |
| 14 | CHEVROLET TAHOE | |
| 15 | CHEVROLET IMPALA |
P0455 Reports by Vehicle
Detailed NHTSA complaint analysis for each vehicle model.
Diagnostic Tips
- Scan all modules, save freeze-frame data, and clear unrelated history codes before focusing on P0455.
- Confirm whether companion codes are present first; they often identify the root cause sooner than the headline DTC.
- Prioritize inspection around fuel/propulsion system and the most common failure path for this code family.
- Graph upstream vs downstream O2 sensor activity at warm idle and cruise; downstream should stay more stable than upstream.
- After each repair step, complete one drive cycle and verify readiness monitors instead of judging success after a quick idle test.
- If the code keeps returning on high-incidence platforms (for example FORD FUSION), check TSB patterns and wiring/connector fitment before major part replacement.
Common Mistakes to Avoid
- ❌ Skipping freeze-frame review and losing the exact RPM/load conditions when the fault set.
- ❌ Installing a catalytic converter before ruling out upstream fueling/misfire conditions that can kill the new unit.
- ❌ Clearing P0455 and returning the car before monitors complete — this often creates repeat visits.
- ❌ Treating intermittent wiring or connector faults as permanent component failure without wiggle testing.
Frequently Asked Questions
Is a large EVAP leak dangerous?
If P0455 is a large leak, why can't I find it?
Why does the gas cap matter?
Why shouldn't I top off the gas tank?
What To Do Next
Possible Fixes
- 🔧 Replace gas cap
- 🔧 Reconnect or replace EVAP hoses
- 🔧 Replace charcoal canister
- 🔧 Replace purge or vent valve
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1
Find your vehicle above
Click your make and model for real owner reports and common causes specific to your vehicle.
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2
Check for recalls
Go to nhtsa.gov/recalls and enter your VIN. Free repairs if covered.
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Get a professional diagnosis
A code alone doesn't identify the exact failed part. A diagnostic ($50–$150) pinpoints the root cause.