P0456 Nissan Altima
EVAP System Leak Detected (Very Small Leak) · Powertrain Code · Low · Repair: Easy
What is P0456?
A very small leak has been detected in the EVAP system. Often caused by an aging gas cap seal, hairline crack in an EVAP hose, or minor seal degradation.
When the Nissan Altima triggers code P0456 (evap system leak detected (very small leak)), it typically points to an issue in the powertrain system. Below you'll find the most common causes, symptoms, and repair options specific to the Nissan Altima.
This repair is rated easy, meaning basic tools, no lift needed.
Diagnostic data on this page is compiled from publicly available repair resources and technical service bulletins. Always have a qualified mechanic confirm the diagnosis before authorizing repairs on your Nissan Altima.
Common Causes on Nissan Altima
- Deteriorated fuel cap O-ring (most common)
- Hairline crack in EVAP line or fitting
- Slight leak at fuel filler neck
- Tiny crack in charcoal canister
Symptoms
- Check Engine Light on
- No driveability symptoms
- Possible faint fuel odor
Notes for Nissan Altima
P0456 indicates a very small leak; a new OE fuel cap resolves this in the majority of Nissan cases.