[Mercedez L.]

This is located on top of the engine on a 1988 Mustang GT 5.0.
How do you know when it is time to change this sensor?

 

[Mercedez L.]

might as well replace it. i think i bought one for 6$.

New or used?
Factory or aftermarket?
Because it is $63.00 From Ford.:headscratch: