P04EC
EVAP System Large Leak Detected Fuel Tank Side
Same as P04EA but the leak is large enough that the system cannot build the test pressure or vacuum at all - typically a missing fuel cap, an unseated hose or a torn vapor line on the tank side.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: easy
Symptoms
- Check engine light on
- Possible smell of fuel near tank or engine bay
- Failed emissions inspection
- Loose-cap warning may appear
Common causes
Ordered by how often each turns out to be the cause.
- Fuel cap missing or not seatedCommon
- Vapor hose pulled off or tornPossible
Parts involved
- Fuel Cap
- EVAP Hose Tank Side
P04EC is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.