Conditions for Setting the DTC: P0338
WARNING: This page is about a different car, the 2008 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.
The ECM detects a difference of more than 250 teeth between reference gap position pulses for 4 consecutive crankshaft revolutions in which the same number of pulses are detected each crankshaft revolution or a cumulative of 50 seconds.