Ford developed the EEC-V system on the 1995-96 models in response to the increased diagnostic requirements for the California Air Resource Board. The regulations developed by the Environmental Protection Agency are designated as the OBD II system.
The OBDII is similar to the OBD I system but not identical. The OBD I requires that the malfunction indicator lamp (MIL) illuminates to inform the driver when an emissions component or monitored system fails. The MIL also lights up to indicate when the PCM is operating in hardware limiting operating strategy (HLOS).
The EEC-V is a evolutionary development from the EEC-IV. None of the components involved are actually new, only the applications have changed.
The only component that has been added is another heated Oxygen Sensor (HO 2 S located behind the catalyst. These downstream sensors are called the Catalyst Monitor sensors (CSM). This means that there are four sensors instead of two.