P0456: Evaporative Emission Control System Leak Detected (Very Small Leak)
17 vehicles · 11 makes · $20-$2,500 repair
Most Reported On
P0456 is an OBD-II diagnostic trouble code meaning “Evaporative Emission Control System Leak Detected (Very Small Leak).” This emissions code means the evaporative emission (EVAP) control system has detected a very small leak — even tinier than the one flagged by P0442, roughly equivalent to a 0.020-inch hole. The EVAP system traps fuel vapors from the tank and prevents them from escaping into the atmosphere, and the computer tests for leaks by sealing the system and watching for pressure or vacuum loss. Because the leak is so small, the cause is often subtle, but a loose or worn gas cap is still the most common and easiest to check. It generally indicates a minor seal, hose, or valve leak somewhere in the fuel vapor system. This code is most commonly reported on 2012-2018 Ford Focus, 2011-2023 Chrysler 300, and 2007-2014 Toyota FJ Cruiser, plus 14 other vehicles, with repair costs ranging from $20 to $2,500.
Common Causes
Typical Repair Cost
Based on 18 documented vehicle-specific issues. Actual cost depends on root cause and vehicle.
Diagnostic Tools
To diagnose P0456, you'll need an OBD-II scanner. Here are our recommendations at every price point.
ANCEL AD310 Classic OBD-II Scanner
by ANCEL
A simple, affordable code reader that reads and clears check engine codes. Great for quick diagnostics on any OBD-II vehicle (1996+).
- Read & clear engine codes
- View freeze frame data
- I/M readiness status
- No batteries or app needed
BlueDriver Pro Bluetooth Scanner
by BlueDriver
Bluetooth OBD-II scanner with a free companion app. Provides enhanced diagnostics, smog readiness, and repair reports sourced from a database of verified fixes.
- Enhanced diagnostics (ABS, SRS, transmission)
- Repair Reports with verified fixes
- Smog check readiness
- Free app (iOS & Android)
LAUNCH CRP123X OBD-II Scanner
by LAUNCH
A professional-grade handheld scanner that reads all four major systems (engine, transmission, ABS, SRS) with live data streaming and graphing.
- Engine, transmission, ABS, SRS diagnostics
- Live data stream & graphing
- AutoVIN for vehicle identification
- Free lifetime updates via Wi-Fi
Autel MaxiCOM MK808S Diagnostic Tool
by Autel
Shop-level diagnostic tablet with bi-directional control, active tests, and full system coverage. Ideal for serious DIYers and small shops.
- All-system diagnostics (25+ modules)
- Bi-directional control & active tests
- Oil reset, EPB, BMS, TPMS, injector coding
- 7-inch touchscreen with Android OS
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Vehicles Affected (17)
Canister Purge Valve Failure Causing Rough Idle and Stalling
EVAP Purge Valve Stuck Open (Hard Start After Refueling)
EVAP Canister Purge Valve Failure
Fuel Filler Neck and Strap Corrosion Causing Fuel Leaks or Tank Movement
Fuel Tank Cracking and Fuel Vapor/Fuel Leak at Tank Seam or EVAP Area
FAQ
What does P0456 mean?
P0456 stands for "Evaporative Emission Control System Leak Detected (Very Small Leak)." This emissions code means the evaporative emission (EVAP) control system has detected a very small leak — even tinier than the one flagged by P0442, roughly equivalent to a 0.020-inch hole. The EVAP system traps fuel vapors from the tank and prevents them from escaping into the atmosphere, and the computer tests for leaks by sealing the system and watching for pressure or vacuum loss. Because the leak is so small, the cause is often subtle, but a loose or worn gas cap is still the most common and easiest to check. It generally indicates a minor seal, hose, or valve leak somewhere in the fuel vapor system.
What are the most common causes of P0456?
The most common causes of P0456 are: Loose, worn, or faulty gas cap or cap seal, Cracked or loose EVAP hose or line, Leaking vent valve or purge valve not sealing, Damaged O-ring or seal at the fuel filler neck, Small crack or leak in the charcoal canister, Leaking fuel tank or sending unit gasket, Loose or corroded EVAP component connection. The specific cause varies by vehicle.
How much does it cost to fix P0456?
Repair costs for P0456 range from $20 to $2,500, depending on the vehicle and root cause.
Which vehicles are affected by P0456?
Au7o has documented P0456 across 17 vehicle models from 11 manufacturers: Chrysler, Dodge, Ford, Hyundai, Infiniti, Kia, MINI, Mazda, Nissan, Subaru, Toyota.
Sources (6)
- ForumReddit r/MechanicAdvice - 2014 Ford Focus Stalling and Rough Idle Due to Canister Purge Valve
- ForumReddit r/ToyotaTacoma thread discussing musty smell in 2016 Tacoma A/C
- ForumMazdas247 Forum - 2006 Mazda5 A/C evaporator leak / dash removal discussion
- TSBFord TSB 19-2207 (NHTSA MC-10169807): 2013-2019 Escape/Focus/C-MAX/Transit Connect — MIL on with DTC P0496 and/or hard start after refueling; EVAP canister purge valve concern
- ForumCarComplaints - Hyundai Elantra Fuel System and Emissions Complaints
- ForumOwner forum discussions on rusted Ranger fuel tank straps and filler neck replacement
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.