I replaced the rear calipers on my 2001 Mustang 6cyl last year. Today the passenger rear caliper started leaking. I am replacing only that caliper. Will I need to bleed both rear calipers or only the one I am replacing? I have bled many brakes in the past but it has always been both sides because I had replaced both calipers. This is a first for me to only have to replace on side. The pads are fine so I don't need to replace them only the pass. caliper.

 

The brakes on all modern cars have 4 independent lines. One line goes to each wheel, so yes you would only bleed the one that you are working on.

 

I assume you are getting that caliper warrantied but technically you should always replace calipers in pairs.