P0456: How to Diagnose & Fix — Evaporative Emission Control System Leak Detected (Very Small Leak)
25 vehicles · 15 makes · $20-$900 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. 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.
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
- Hesitation during acceleration from a stop
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. Clear all stored codes after replacement and drive through one complete drive cycle to verify the fix.
Sources for this issue (4)
Ford Transit Connect · 2014–2021
Owners report extended cranking, rough idle, or stalling shortly after refueling due to an EVAP canister purge valve that sticks open and floods the intake with fuel vapor. This failure mode is documented across Ford applications and appears in Transit Connect owner reports and service literature addressing purge valve performance. The condition often triggers EVAP-related DTCs and can worsen over time.
Common Symptoms
- Hard start immediately after refueling
- Rough idle or stumble after fill-up
- Occasional stall when coming to a stop
- Fuel odor near engine bay
- Check engine light on
How to Fix
Replace the EVAP canister purge valve/solenoid and inspect EVAP lines for liquid fuel contamination. Clear codes and verify proper purge operation with scan tool commands; advise against topping off the tank to reduce recurrence risk.
Sources for this issue (1)
MINI GP · 2013–2021
MINI turbo models have documented EVAP purge/vent valve failures, causing hard starts and rough idle.
Common Symptoms
- Rough idle or stumbling
- Check Engine Light with EVAP-related codes
How to Fix
Replace the EVAP purge valve (tank vent/purge solenoid as applicable by engine) and inspect EVAP lines for cracks or disconnections. Clear codes and verify proper purge operation with scan-tool activation tests; ensure the fuel cap and filler neck seal correctly.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine MINI GP2 fuel-tank breather valve 13907624542OEMMINI 13907624542
Confirm VIN and ho
- Genuine MINI GP3 fuel-tank breather valve 13907621174OEMMINI/BMW 13907621174
VIN-confirmed 2020-2021 F56 GP3/B48E purge-valve stuck-open or failed-command branch Fitment/availability: The inspected direct U.S.
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 (2)
Kia Rio · 2001–2011
Ford Explorer · 2011–2020
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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 $900, depending on the vehicle and root cause.
Which vehicles are affected by P0456?
Au7o has documented P0456 across 25 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.