Cylinder 7 Deactivation/Intake Valve Control Circuit/Open. what does this mean?

Question

Went to get emissions done today and failed because of the code p3449 with no check engine light on or any other dummy light. When I typed the code in online it came up as (Cylinder 7 Deactivation/Intake Valve Control Circuit/Open) I'm not quite sure what that means.

Answer 1

P3449 MDS solenoid 7 circuit

MDS is multi displacement system which deactivate cylinder 1 ,4 , 6 ,7. So you can go from 8 cylinder engine to a 4 cylinder 8 cylinder for heavy loads and accleration and 4 cylinder for cruising and city traffic. MDS solenoid do fail. Because this is a solenoid it is capable of shorting the MDS number 7 driver circuit of the ECM. For now the solution is to replace the MDS number 7 solenoid.