Purpose – The purpose of this paper is to demonstrate that through the maintenance systems theory an audit methodology can be developed so it can be linked to a decision making process methodology to fully support the actions and initiatives proposed for improvement. Design/methodology/approach - The methodology is delimited by the concept of maintenance systems, from where a maintenance audit is developed to allow an integration of the Decision Making Grid (DMG) concept in order to add a basis of decision making and help in the prioritization process. Findings – This paper discuss an approach to the maintenance audits integrating well-established concepts of maintenance engineering and a decision making technique, which leads to an audit result-decision matrix that can show to the organization the wrong paths and shortcomings that are required to be solved in order to progress and close the gap to reach their desired performance. Originality/Value – Although there is a wide range of techniques developed to assess and audit, most of them imply a large and elaborated method not only for the questions (which are inevitable when assessing) but also to understand the findings and elaborate recommendations. The paper explores the integration of a defined maintenance system, its boundaries and its interactions, while mapping those concepts within a decision matrix.