P3449, P3441, P3425, P3401 are all fault codes relating to the MDS system on the Hemi 6.4 V8.
The MDS also known as the cylinder deactivation is an emissions and fuel saving system used on these V8 engines. It effectively shuts down cylinders on the vehicle when they are not required.
There are a number of weaknesses with these engines, the most common is the hydraulic lifter failure on these cylinders which in turn cause damage to the camshaft. This fault can be avoided by doing what’s called a MDS delete.
This upgrade involves the replacement and upgrade of the cam shaft, the removal of the cylinder heads in order to change the lifters, the MDS solenoid deletes and retuning the vehicle. This upgrade can be done at GDL but is not the subject of this article.
If you are seeking more information about the MDS delete you can read up on it by clicking the link below.
The codes listed at the start of the article mean a failure of one of the four MDS solenoids. In order to clear those faults the specific solenoid will need to be identified and replaced. This requires the removal of the inlet manifold.
It has been noted that it is common for these fault codes to log when the fault is with the wiring lume sitting beneath the inlet manifold and is not always the solenoids itself.
Before replacing the solenoid remove the manifold and inspect that harness for damage.
This short video shows the damage that is common for this engine, the lume and the codes in question.