Rainy Days and HV system

Hi all,

It rarely rains where I live, but for the past 3 rains we got, a day after the rain I got the triangle of death and the scanner shows a problem with the HV system. I clear it with a scanner but it returns when it rains again.. Does anybody have an idea what this is due to or it might be a pure coincidence that I got rain and death triangle the past three times. Please help if you had a similar experience.