Code Definition

P0456 — Evaporative Emission System Minor Leak

System: Powertrain  |  Type: Generic (OBD-II Standard)  |  Make: Generic

About P0456

P0456 is a generic (obd-ii standard) powertrain diagnostic trouble code. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

Because P0456 is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

The ECM sets P0456 when it detects a very small leak in the EVAP system. This occurs when the system fails to maintain the expected pressure or vacuum during self-diagnostics, indicating a minor vapour loss. Unlike P0455 (gross leak), this code signifies a small but measurable leak.

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