Powertrain, generic · Auxiliary emission controls

P04ED EVAP System Large Leak Detected - Fresh Air Side

Check engine lightOn

EmissionsRelevant

Drive cycleRequired

Limp modeNo

Hybrids with a sealed fuel tank have a valve separating the tank from the charcoal canister and its vent side. CARB allows such sections to be leak-checked separately with their own codes; a Ford patent checks the tank side via tank pressure with the valve closed and the canister side with a leak check module. Conventional systems report the same leak as P0442, P0455 or P0456. P04ED reports a large leak in the canister and vent section: the leak check module builds up no meaningful vacuum – line off, canister broken, vent valve open. Purging may be suspended. No manufacturer document available to us names this code; the description follows CARB and the Ford patent.

Likely causes

Line at the canister or leak check module off or broken

Vent valve or leak check module not closing

Canister housing cracked

Purge valve stuck open

Symptoms

Check engine light on
Possibly check fuel cap message or slight fuel smell
No change in driving

Repair estimate

DifficultyMediumWorkshop job

Parts and labour€40–450

Time0.5–2.5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

charcoal canisterevap vent valveleak check moduleevap hoses

Related codes

P04EB P04EC P04EF P0455 P0446

References: law.cornell.edu, patents.google.com.