Clean the surface of the roof under the flashing.
How to repair leaky roof flashing.
Isolate areas when you run the hose.
Plug pinholes with roofing cement and patch holes up to about 3 4 inch in diameter with a patch from the same material as the flashing.
Small nail holes left behind from old vents satellite dish brackets or anything previously attached to the roof can allow water to enter and cause damage for years before leaking is noticed.
If a leak is difficult to find enlist a helper and go up on the roof with a garden hose.
First roughen the area around the hole with a wire brush or sandpaper and then clean it.
Start low soaking the area just above where the leak appears in the house.
Spread some roofing tar under the edge that is sticking up and bend it back down to a flat surface.
Use a roofing nail to keep the section down and apply some caulking around the edge to seal against water.
Step 3 remove metal roof flashing.