Z02.89 and Z04.89 are roughly equivalent but Z04.89 is a little less specific - if you feel this is an administrative exam, then go with Z02.89. I would use Z04.89 only because the of the legal reference I cited which doesn't appear in any of the descriptions under Z02. But we're kind of splitting hairs at this point and I think it's unlikely to make a difference one way or another. The payer you're submitting this to may have more guidance on this but sometimes you just have to select what you think is most appropriate and if it causes a problem down the road, deal with it then. You won't find written guidelines for every situation you find in coding!