At Brighton Reticulation we give a 12 month warranty on all of our work, which covers most mechanical and electrical functions.
We use Rainmaster control boxes which have a 5 year warranty, possibly one of the best you can find.
Sprinkler nozzles are slightly different issue as they can block up quite randomly due to dirt and grit in the waterline. We always thoroughly flush the water line before installing nozzles, and then check that they function before finishing the job. But dirt and grit is beyond our control and for that reason we offer a 30 day warranty on nozzles blocking.