Nodules from fillers are usually a collection of material that has also formed collagen around it. If it's a hyaluronic acid filler such as Juvederm or Restylane, it can be dissolved with hyaluronidase and it will go away within a couple of hours - and that's what should be done. If it is from Sculptra or Radiesse, it can be injected to break it up. So, the type of treatment depend on the filler, but it should not be permanent unless it is a permanent filler like Artefill or silicone.
If a temporary filler causes a nodule, it will typically resolve. You can try to massage it or (if it is an HA), having your injector give you some Hyaluronidase. If it is a permanent filler, such as silicone, the nodule may not go away.
A filler when injected can cause a nodule of product, a small hematoma, or a granuloma. If it is product and you jsut had it injected, you can often massage it down a bit. If it is product and it was injected several weeks ago, hyaluronidase can be used to dissolve the product.