The info posted by Uffex is exactly right, what it doesn't say , it's based on all sensors in good working order. Unfortunately, until you see the graph plotted out in techtool, you really don't know. Most often it will be one of 2 things. Either the burner will have developed a crack or the burner temp sensor has become lazy. If the computer doesn't see that each stage is reaching the desired temp, it assumes a fuel leak has occurred and aborts regeneration attempts. I know of no other alternative software to observe EATS values in operation.