Powertrain, generic · Auxiliary emission controls
P04EA EVAP System Small Leak Detected - Fuel Tank 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. P04EA reports a small leak (0.040 in) in the tank section – tank, filler neck, cap and lines up to the tank valve. No manufacturer document available to us names this code; the description follows CARB and the Ford patent.
Likely causes
Fuel cap or seal leaking or not closed properly (tether trapped)
Filler neck or tank vent line leaking
Sender or pump flange seal leaking
Tank valve or tank pressure sensor faulty
Symptoms
- Check engine light on
- Possibly check fuel cap message or slight fuel smell
- No change in driving
Repair estimate
DifficultyMediumDIY possible
Parts and labour€20–500
Time0.2–3 h
Typical range across vehicles; the real cost depends on what the testing finds.
Parts involved
fuel tankfuel capfuel tank isolation valvefuel tank pressure sensor
Related codes
References: law.cornell.edu, patents.google.com, newtonnet.co.uk.