P0456 on RAM: How to Diagnose & Fix
Evaporative Emission Control System Leak Detected (Very Small Leak)
1 RAM model · 1 documented issue
P0456 on RAM by model: symptoms, diagnosis and fix
2019 Ram owners report a check-engine light and P0456, sometimes recurring after a reset. Purge valves and capless filler seals are suggested in the discussions, but the inspected reports do not establish either as the failed part on every truck. A diagnostic code alone is not a parts diagnosis. 2019 Ram 1500 DT gasoline owner reports. Diagnostic bulletin 18-048-23 covers 2012–2023 Stellantis gasoline vehicles with the available wiTECH Small Leak Verification Test; its broader procedure scope does not broaden the years of these owner reports. Diesel trucks are excluded from this card.
How to Fix
Have a qualified shop read the code and follow the vehicle EVAP diagnostic procedure before buying a filler assembly or purge valve. Bulletin 18-048-23 requires the wiTECH Small Leak Verification Test first to verify a leak, then again after component repair or replacement to confirm the fix; it explicitly includes PCM software updates for P0456. Repair the identified cause rather than assuming the pictured filler is faulty. A road test alone will not confirm this repair. The bulletin is information-only and does not promise warranty coverage; confirm any applicable emissions coverage for the diagnosed part and vehicle separately.
Sources for this issue (4)
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 on a RAM?
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. On RAM it is documented across 1 model: 1500.
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 on a RAM?
Repair costs vary widely with the root cause and RAM model; each issue on this page carries its own estimate where one is published.
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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.