Code 21
WARNING: This page is about a different car, the 1994 Eagle Vision, 1994 Dodge Intrepid, and 1994 Chrysler Concorde. However, it is still accessible from the selected car via links, so may be relevant.
DRB displays O2S STAYS AT CENTER, LEFT O2S STAYS AT CENTER, or RIGHT O2S STAYS AT CENTER. Condition is: no rich or lean signal detected from oxygen sensor input.
DRB displays O2S SHORTED TO VOLTAGE, LEFT O2S SHORTED TO VOLTAGE, or RIGHT O2S SHORTED TO VOLTAGE. Condition is: oxygen sensor input voltage maintained at more than normal operating range.