Possible Causes

WARNING: This page is about a different car, the 2003 Mazda Protege5 and 2003 Mazda Protege. However, it is still accessible from the selected car via links, so may be relevant.

Open or Short circuit between VTCS solenoid valve and PCM.
Open circuit between VTCS solenoid valve and main relay.
Poor connection of PCM or VTCS solenoid valve connectors.
VTCS solenoid valve malfunction.
PCM malfunction.