INDEPENDENT REFERENCE
P0456 — EVAP system very small leak detected
Generic powertrain DTC · LOW priority for follow-up (not a certified safety rating)
What the code means
EVAP monitor detected a very small vapor leak.
What you might notice
Usually no driveability symptom beyond warning light.
Possible causes — not a diagnosis
Fuel cap seal; microcracks in hoses; small vent/purge valve leaks.
Useful diagnostic checks
Perform cap inspection and an approved small-leak test; monitor after repair.
Next steps
Do not assume the cap is always responsible.
Related OBD-II codes
These generic definitions are explanatory summaries of commonly standardized OBD-II powertrain conditions. Vehicle-specific code logic and service procedures must be verified against manufacturer documentation. EPA: On-board diagnostics.