Sometimes when your engine develops a fault, the problem is not immediately obvious. This is when people often ignore the problem hoping it will go away, yet it develops into something more serious. It's also where diagnosis and repair at a professional garage can get quite costly. Tools such as these compression testers are designed to try and enable you to diagnose engine problems yourself, either allowing you to go on and make the repairs or take it to a professional with a clear statement of the problem. These compression testers allow you to check the compression in your engine's cylinders, giving clear readings over the performance of the engine.