OBD-II Fault Code

P0455: Evaporative Emission Control System Leak Detected (gross leak)

Meaning, symptoms, likely causes, diagnostic checks and repair guidance for P0455.

System family

Powertrain

Generic/SAE

Repair category

EVAP / fuel vapour

Use this category to narrow your checks before replacing parts.

Severity

Low

Severity is a general guide. Confirm with scan-tool data and vehicle symptoms.

What P0455 usually means

Evaporative Emission Control System Leak Detected (gross leak).

Common symptoms

Check Engine light; Poor drivability or reduced fuel economy depending on fault; Fuel smell possible; Usually little drivability change

Likely causes

Loose/damaged fuel cap; Cracked EVAP hose; Faulty purge/vent valve; Leaking canister

Diagnostic checks

Scan all modules and record freeze-frame data before clearing codes; Check battery voltage and related fuses; Check fuel cap seal first; Smoke-test EVAP system; Command purge/vent valves with scan tool if available

Repair guidance

Replace damaged cap/hoses, repair leaks, replace stuck purge or vent valve after testing

Verification after repair

Clear code, road-test through the same drive condition, then rescan

Note: Confirm vehicle make/model/year because manufacturer-specific codes can vary. A DTC identifies a circuit or system condition, not always the failed part.