What this tool is looking for
Most lawn problems show a pattern. Brown seams on new sod usually point to water or soil contact. Dry arcs near sprinkler heads point to coverage. Soggy low spots point to grading, drainage, or overwatering. Thin grass under trees points to shade pressure or the wrong grass choice.
What to check before replacing sod
Run each sprinkler zone for a few minutes, touch the soil in problem areas, look for runoff, and compare sunny edges against shaded sections. If the issue follows one sprinkler zone or one low spot, replacing the sod without fixing that cause can waste money.