coach leaves for a few minutes
 

In a high school game last night, and during a live ball, I noticed that there was not a coach on the bench for the home team. And, there were no assistant coaches either.

I asked my partner if she knew of a rule requiring A coach to be with the team during live ball, but she wasn't sure either.

I found out the coach went to the bathroom and by the time I found out she was walking back. We wasted 3 minutes on this.

Is this a violation and if so, what is the penalty??

I'm not sure how you would notice an MIA coach during a live ball, but assuming you are using NFHS Rules:

Rule 6-1 defines a team member as "Team members consist of all school representatives located in the team bench area, including but not limited to coaches, teammates, managers, trainers and the players."

Rule 9-1-1 states that "All nonplaying team members shall be seated on the designated team bench during the set. The head coach may stand during the set in the replacement zone, subject to Rule 12-2-6."

However, there is no penalty for this violation. Personally, if a coach needed to go to the bathroom, what options would you have other than to let them go? Deny them? Issue a yellow card if they take more than a minute? Hold up the match until they get back? I'm not sure why you wasted three minutes. For me it wouldn't be an issue until such time as I needed said coach for a reason, such as submitting the next set's lineup.

coach leaves
 

Well, the reason I knew the coach was gone during the live ball was that I was the R2, and my job is to look at the bench and see if there are subs or the coach wants a time out. At the moment I noticed the coach gone, the R1 signaled serve, so i went with the play. Most officials should scan the coaches just before signal to serve.

there may not be any violation, but have you considered the liability if one of the players got hurt and there was not a coach on the bench. There may not be anyone available to tend to the injury.

This took 3 minutes, but it wasn't until the end that i knew the coach was in the bathroom.

If this happens again, i would do the same...stop the game until there was someone of responsibility to handle the team.

I have learned over the years that being competent is as important as following the rules.

By rule, there is no requirement for a coach to be present on the bench during play. Where was your site manager during this situation? I would have stopped the match and gotten site management involved. The site manager could possibly sit on the bench for liability purposes, however since only the head coach attended the pre-match conference, anyone else is relegated to sitting on the bench only - no standing and coaching allowed.