Powertrain, generic · Auxiliary emission controls

P04EB EVAP System Small 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. P04EB reports a small leak (0.040 in) in the canister and vent section – canister, vent valve or leak check module, dust filter and lines up to the purge valve – typically checked with the leak check pump with the engine off. No manufacturer document available to us names this code; the description follows CARB and the Ford patent.

Likely causes

Crack or leaking connection at the canister or vent lines
Vent valve or leak check module not sealing
Purge valve leaking
Rodent bite or chafing on lines under the car

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€50–450
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

P04EAP04EDP04EFP0442P0446

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