DTC P0457:00 [MZI-3.7]: Notes

WARNING: This page is about a different car, the 2009 Mazda 6. However, it is still accessible from the selected car via links, so may be relevant.

DETECTION CONDITION & POSSIBLE CAUSE

DTC P0457:00	Evaporative emission system leak detected (fuel cap loose/off)
DETECTION CONDITION	P0457:00 indicates that the initial vacuum could not be achieved after a refueling event and the purge vapor flow is excessive (gross leak).
POSSIBLE CAUSE	Missing or loose fuel filler cap. PCM malfunction