Codes "Possible Causes"
Harness is open or shorted
It means that the wire(s) connected from and to the component (sensor, solenoids, actuator, etc.) is either open (cut, broken, disconnected) or shorted (touching other wires, components, body). "Open" and "short" are common electrical terms. An open is a break in a wire or at a connection. A short is an accidental connection of a wire to ground or to another wire. In simple electronics, this usually means something won't work at all. With complex electronics (such as ECMs or PCMs) this can sometimes mean something works, but not the way it's supposed to.
Circuit poor electrical connection
It means that the component (sensor, solenoids, actuator, etc.) connector is not fully connected or is disconnected. Before replacing any components, try fully disconnecting the connector, reconnect and test the system or component again.
Faulty or Failed component
It means that the component it's more than likely the cause of the code and that needs to be replaced
Engine mechanical problems
When a code list as possible causes an engine mechanical problem, it means that the problem is not caused by electronic component, but rather by a mechanical component such as pistons, valves, mechanical pump