DTC will set when the following conditions are present:

WARNING: This page is about a different car, the 1997 GMC Pickup and 1997 Chevrolet Pickup. However, it is still accessible from the selected car via links, so may be relevant.

Engine speed is less than 4000 RPM.
MAF sensor is at least 5 gm/s.
Crank sensor duty cycle is greater than 50 percent (or the ratio high ref/low ref is greater than 5.66).