What does it mean?
P3449 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Cylinder 7 Deactivation Solenoid Control Circuit .
Symptoms
- MIL (check engine lamp) on and cylinder deactivation disabled
- Fuel consumption noticeably higher because the engine cannot run on reduced cylinders
- Rough idle and vibration if the cylinder 7 valve stays collapsed
- Ticking or clacking noise from the cylinder head on that bank
- Cylinder 7 misfire, sometimes with matching misfire codes
- Slightly weaker throttle response
Likely causes
- Solenoid connector unlatched, backed out or with a terminal displaced inside the housing
- Broken control wire between the module and the valve lifter oil manifold on that bank
- Oil creeping up the harness and coating the terminals until they no longer conduct
- Open winding inside the cylinder 7 deactivation solenoid
- Blown fuse or open supply feed shared by the deactivation solenoids
- Damaged harness section running under the intake manifold, often after earlier repairs
How to fix it
- Confirm the cylinder numbering and which bank cylinder 7 sits on before you probe anything
- Read and record freeze frame data before clearing the code
- Unplug the cylinder 7 solenoid and inspect its terminals for oil film, corrosion and push-back
- Measure coil resistance at the solenoid; an infinite reading confirms an open winding
- Check continuity of the control wire to the module connector and verify supply voltage with the key on
- Wiggle the harness while monitoring resistance to reveal an intermittent open
- Repair the wire or terminal or fit a new solenoid, then command the output with a scan tool to confirm current flows