DTC P1512: Variable Tumble Control System Stuck Closed: Condition

WARNING: This page is about a different car, the 2002 Mazda Protege5 and 2002 Mazda Protege. However, it is still accessible from the selected car via links, so may be relevant.

DTC is set when PCM detects air flow is more than 45.2 gram/sec. when engine speed is more than 3000, engine coolant temperature is more than 158°F (70°C), and throttle valve opening angle is more than 75 percent. This is a continuous monitor. MIL is illuminated when PCM detects malfunction during 2 consecutive drive cycles. Possible causes are:

Crankshaft Position (CKP) sensor malfunction.
EGR boost sensor malfunction.
Engine Coolant Temperature (ECT) sensor malfunction.
Intake Air Temperature (IAT) sensor malfunction.
Mass Airflow (MAF) sensor malfunction.
PCM malfunction.
Short circuit between PCM and VCTS solenoid valve.
Throttle Position (TP) sensor malfunction.
Variable Tumble Control System (VTCS) solenoid valve malfunction.
VTCS shutter valve stuck closed.
VTCS shutter valve actuator stuck closed.