Powertrain
generic / SAE
P0456
Evaporative Emission System Leak Detected (Very Small Leak)
A very small leak (typically equivalent to a 0.020 inch / 0.5 mm orifice) has been detected. Smaller threshold than P0442; intermittent and often weather-dependent. Modern OBD-II requires this monitor on most vehicles since model year 2000.
SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number4 / 56
Possible causes
- Fuel cap seal hardened or worn high
- Purge or vent valve leaking slightly medium
- Hairline crack in EVAP hose medium
Symptoms
- Check engine light on
- Possible smell of fuel near tank or engine bay
- Failed emissions inspection
- Loose-cap warning may appear
Inspection / repair
- Difficulty: medium
- DIY: possible
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References
sae:J2012