Brown patches on your lawn can be caused by a number of factors - one of which can be your irrigation system.
Below are a few common irrigation system causes:
Incorrect sprinkler head height can cause brown spots and poor lawn growth.
Sprinkler heads that have been installed too low aren't able to rise above the ground or turf level, or the level of the plants directly around them. Low sprinkler heads prevent the water from spraying properly, and can lead to coverage gaps and flooding around the sprinkler head.
If sprinkler nozzles are clogged by dirt or debris the sprinkler head may be prevented from spraying properly, causing gaps in the spray pattern, which will lead to brown patches.