P0456: How to Diagnose & Fix — Evaporative Emission Control System Leak Detected (Very Small Leak)
28 vehicles · 15 makes · $20-$1,800 repair
How to diagnose and fix P0456: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Ford Focus · 2012–2018
The 2012-2018 Ford Focus with the 2.0L GDI engine experiences frequent canister purge valve (CPV) failures that cause rough idle, stalling, difficulty starting (especially after refueling), and fuel-related DTCs. The purge valve sticks open, allowing fuel vapors to flood the intake manifold at inappropriate times. This is separate from the carbon buildup issue and is one of the most commonly replaced components on the 2012-2018 Focus. Ford recalled 2012-2018 Focus cars with the 2.0L GDI and 2.0L GTDI (ST) engines under safety recall 18V735 (Ford 18S32) because a malfunctioning CPV can create excessive vacuum in the fuel vapor system and stall the engine; follow-up recalls 19V515 (Ford 19S22) and 26V369 (Ford 26S40) cover cars whose PCM update was missed or done incorrectly. The problem affects both manual and automatic (PowerShift) transmission models. Focus Fanatics Forum documents this as one of the top five most-replaced parts on the Mk3 Focus.
Common Symptoms
- Rough idle or engine surging at idle
- Engine stalling after starting, especially after refueling
- Difficulty starting the engine (extended crank time)
- Check engine light with EVAP system codes
- Fuel smell from engine bay
- Hesitation during acceleration from a stop
- Engine runs rich (black exhaust smoke)
How to Fix
First check the VIN for open recalls 18V735 (Ford 18S32) and 26V369 (Ford 26S40), under which dealers repair the purge system at no charge. Otherwise replace the canister purge valve (Motorcraft CX-2571 or equivalent, $30-60 part). The valve is located on top of the engine near the intake manifold and is a 15-30 minute DIY job. Use the updated Ford part number to avoid repeat failures. Clear all stored codes after replacement and drive through one complete drive cycle to verify the fix. If codes P0452/P0453 persist after purge valve replacement, the fuel tank pressure sensor may also need replacement.
Sources for this issue (2)
Chrysler 300 · 2011–2023
Evaporative emission control system develops small leaks triggering P0456 code. Most commonly failed gas cap, chaffed EVAP purge pipe harness, or failed purge solenoid. Triggers check engine light and prevents emissions testing pass.
Common Symptoms
- Check engine light with P0456 code
- "Gas cap" warning even with cap tight
- Fuel smell near vehicle
- Failed emissions test
- No performance or drivability issues
How to Fix
Start with gas cap replacement ($20-40). If code returns, smoke test EVAP system to locate leak. Common fixes: replace purge solenoid, repair chaffed wiring harness, or replace cracked EVAP hoses.
Sources for this issue (1)
Dodge Journey · 2009–2020
AC compressor fails due to inadequate lubrication, leaky seals, and internal mechanical failure. Evaporator develops leaks from age and moisture. Condenser prone to damage from road debris. Lack of lubrication from leaks causes compressor seizure.
Common Symptoms
- AC blows warm air
- AC works intermittently
- Compressor clutch not engaging
- Loud grinding or squealing from compressor
- Musty odor from vents (evaporator mold)
How to Fix
Diagnose AC system to identify leak source. Replace failed compressor ($400-800), evaporator ($300-600), or condenser ($200-400) as needed. Flush AC system when replacing compressor. Replace receiver/drier whenever system opened.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Mopar 55111410AF complete A/C compressor
Replace a compressor confirmed failed on the listed configuration Fitment: 2016-2020 Journey 2.4L on the product fitment table; not the 3.6L compressor Live OEM direct-product page when checked
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Sources for this issue (1)
Ford Transit Connect · 2014–2021
MINI GP · 2013–2021
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P0456 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
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 $1,800, depending on the vehicle and root cause.
Which vehicles are affected by P0456?
Au7o has documented P0456 across 28 vehicle models from 15 manufacturers: Acura, Chrysler, Dodge, Ford, Honda, Hyundai, Infiniti, Jeep, Kia, MINI, Mazda, Nissan, RAM, Subaru, Volkswagen.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.