WHAT CODE PO140 MEANS on 1997 Dodge Ram 2500

ON DODGE RAM VAM 1997 2500

Asked by for the 1997 Dodge Ram 2500
It means the ecm has detected a problem with the rear o2 sensor or circuit. USUALLY replacment will fix this but not always.
Circuit can be checked with a DVOM. Or just take a shot at it with a new sensor.