Angular 2 can't find a component declared in my feature module

I guess you should export it like:

@NgModule({
    imports:[CommonModule, FormsModule],
    declarations: [PageHeaderComponent],
    exports: [PageHeaderComponent]
})
export class AppCommonModule { } 

This way other components could use the component.

Otherwise PageHeaderComponent will only be available inside of AppCommonModule

See also

• https://angular.io/docs/ts/latest/guide/ngmodule.html#add-the-contactmodule

We export the ContactComponent so other modules that import the ContactModule can include it in their component templates.

All other declared contact classes are private by default

• https://angular.io/docs/ts/latest/cookbook/ngmodule-faq.html#!#q-what-to-export

Export declarable classes that components in other modules should be able to reference in their templates. These are your public classes. If you don't export a class, it stays private, visible only to other component declared in this module.