Trouble code
P0456
Evaporative Emission System Leak Detected (Very Small Leak)
What P0456 means
A very small vapor leak, the tightest threshold the system tests for.
Symptoms you may notice
- Check engine light only
Common causes, cheapest first
- Fuel cap seal
- Hairline crack in an EVAP line
- Slightly leaking vent valve
Before you buy anythingReplace the fuel cap with a proper one for your vehicle before spending anything else. Cheap universal caps are a common cause of a code that will not clear.
What to do next
- Confirm the code with your own scan tool, or have it read free at a chain parts store.
- Decode your VIN so you know your exact engine and build date.
- Work down the causes above from cheapest to most expensive.
- Search NHTSA for a recall or service bulletin covering this symptom on your vehicle.
- Read the engine buying guide before ordering.
P0456 is a generic OBD-II code, standardized across every make and model sold in the US from 1996 onward. The meaning is the same on any vehicle; the specific part and its location are not.
Parts
Parts commonly needed for P0456
These go to Amazon. We earn a commission if you buy, at no extra cost to you — see our affiliate disclosure. Which one you actually need depends on diagnosis — read the note above first.
Confirm fitment against your VIN on the listing page before ordering. A part that matches your year and model can still be wrong for your build date or engine code.