Corrective maintenance is a form of system maintenance that is performed after a fault or problem emerges in a system, with the goal of restoring operability to the system. In some cases, it can be impossible to predict or prevent a failure, making this type of maintenance the only option. In other instances, a system can require repairs as a result of insufficient preventive maintenance, and in some situations, people may opt to focus on corrective, rather than preventive, repairs as part of a maintenance strategy.
The process of corrective maintenance begins with the failure and a diagnosis of the failure to determine why it appeared. The diagnostic process can include a physical inspection of a system, the use of a diagnostic computer to evaluate the system, interviews with users, and a number of other steps. It is important to determine what caused the problem in order to take appropriate action and to be aware that multiple failures of components or software may have occurred simultaneously.
The next step is replacement of damaged components or software. In some cases, the damage may be repairable, either in situ or by removing the item in question and doing repairs off site. In other instances, full replacement with a new item may be required to restore the system's functionality. For example, if an optical drive in a computer fails, a technician may determine that replacing part of the drive or repairing part of it may be sufficient, or may find that the entire drive needs to be scrapped so that a new one can be inserted.
After the maintenance is performed, a technician verifies that the fix has worked by testing the system. This may be done in several stages to confirm that the system is operational slowly before overloading it with tasks. Verification is especially important on systems sent in to a facility for repair, as the technicians want to be sure that when they are sent back out, the users will be happy with the standard of the work performed.
For some older systems, it may make more sense to rely on corrective maintenance. Preventive maintenance can be expensive, and with these systems, it may not be practical; it may be more cost effective to simply repair system components as they go wrong. By contrast, with a newer system, preventive maintenance can save money in the long term and extend the life of the system by preventing system failures as much as possible before they happen.