Anyone know if all of the PS computers are interchangeable?

 

I believe the S4's computer is based on RPM and the S5's are based on Speed, so i'm going to say no.

 

sort of the same and not at all the same.

The S4 power steering computers are all the same, but only some of the S5 power steering computers are the same as the S4.

See many of the non turbo S5 models came with the inferior engine speed sensing steering. On those models the power steering computer is different than the Turbo models or the S4 models with power steering and the S5 models with vehicle speed sensing power steering.

 

Thanks, Mark. I have an S4, so you've saved me from getting the wrong one.