Don't Panic! There only a few ways autoclave testing can FAIL and below you will find the types of failure; their causes and what you can do.
Failed Biological/Spore Test
Biological tests are usually considered the most important test as they best reflect whether biological materials remain on your instruments.
Operator error is the most common reason for a failed spore test. If your autoclave has automatic controls and completing cycles without giving any failure messages, the chances are that the causes of a failed spore test were due to some type of operator error. You may need to review the sterilization procedures your staff has been using to see if you could identify the problem. Firstly you have to make sure that they are not overloading the Autoclave. Check the manufacturer’s specifications in regards to how the sterilizer should be loaded. The next thing you will need to check is the time and temperature settings. It is possible that the factory default settings somehow got changed or the operator is simply not running the sterilizer hot enough or long enough. Manufactures default settings can vary a little but generally an autoclave has to maintain 270F degrees Fahrenheit for 12 minutes. Lastly if the Autoclave uses manual controls, you will need to monitor and record"
Failed Control Test
To ensure that the microorganisms are working it is required that a positive control tube or vial is set aside (a bacterial vial that hasn't been in the autoclave). If the control vial does not go through a color change, that means that the control vial was not viable to begin with.
Reasons that it could fail is:
Failed Chemical Test
Check the mode? Check the manufacturer settings?