Most European directives allow for some form of self-certification under Module A. Self-certification means that you do not need a notified body at all for the conformity assessment procedure. You must identify what standards apply to your product and establish conformity with the appropriate directive yourself, this will include carrying out the required tests. Formally this is called internal production control. If you produce multiple iterations of a product you must establish conformity against the initial design for each product.
Sometimes directives do not allow Module A but they will allow either Module A1 or A2. Module A1 means you are still responsible for the conformity assessment, like Module A, but you will need to carry out the product tests under the supervision of a notified body. What tests must be carried out are usually documented in the applicable directive. For example, in RCD 2013/53/EU the tests that must be carried out are described in Annex VI and relate mainly to stability, noise and exhaust emissions.
Use the tool below to determine if you can use Module A or Module A1 for the RCD 2013/53/EU.