Fault Family System: Powertrain (P-Codes) 8 SAE Codes

EVAP Small Leak

Diagnostic & Technical Explanation

Code P0440 (EVAP System) sets when the EVAP leak-detection monitor cannot hold vacuum or pressure in the fuel vapor system within its small-leak threshold (typically a 0.020 in. equivalent orifice), including the tighter very-small-leak threshold and the fuel-tank-side/fresh-air-side variants used on natural-vacuum leak detection systems, or when the general EVAP system monitor itself fails. The dominant causes are a loose or worn fuel filler cap, a cracked EVAP hose, or a purge/vent solenoid that no longer seals.

These 8 diagnostic trouble codes share one detection mechanism and one repair path, which is why MechanicDB groups them into a single authored fault family rather than repeating the same explanation 8 times.

Codes in this family (8)

Code	Definition	Repair coverage
P0440	EVAP System	4 ranked fixes
P0442	EVAP System Leak Detected (small leak)	4 ranked fixes
P0456	EVAP System Leak Detected (very small leak)	4 ranked fixes
P0457	EVAP System Leak Detected (fuel cap loose/off)	4 ranked fixes
P04EA	EVAP System Small Leak Detected - Fuel Tank Side	4 ranked fixes
P04EB	EVAP System Small Leak Detected - Fresh Air Side	4 ranked fixes
P04EE	EVAP System Very Small Leak Detected - Fuel Tank Side	4 ranked fixes
P04EF	EVAP System Very Small Leak Detected - Fresh Air Side	4 ranked fixes

What this page does not show

This page publishes the fault mechanism and the code index. The licensed dataset adds, for every one of the 15,886 codes, the full authored repair set (56,729 procedures in total) with the fields deliberately withheld here:

Procedures 2..n after the first-listed procedure
Aftermarket parts cost ranges in USD (est_parts_cost_min/max_usd)
Professional labor-hour estimates (est_labor_hours)
Step-by-step diagnostic and repair instructions
Replacement-part mappings and catalog lookups
6,637 manufacturer-specific OEM codes across 32 makes ($149 tier)

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