way that labor is covered is if Nissan installs them. If not installed by Nissan you eat the labor. The reworked injectors have a 90 day warranty, labor is covered if installed by us. If not installed at Z1 you have to take care of labor. We have had one incident where an injector went bad 4 months later but we went ahead and sent the guy another. If you have anymore questions feel free to email me.