I have a knocking under the dashboard on the passenger side
does it happen when you do something eg accelerate, turn, try to start . is the CEL on
It could be a heater control servo motor stuck and making a knocking sound, try changing mode controls or just turning the HVAC system off when you hear it and listen for it to stop, it might take a few for everything to shut down on the unit.
Believe it or not, it could be the right front strut.
Looking for a Used Sable in your area?
CarGurus has 1,296 nationwide Sable listings starting at $1,000.
Search Mercury Sable Questions
Mercury Sable Experts