It could turn out that nothing happens - the court accepts your explanation; it could turn out that you are put into rehab; it could turn out that you are required to do some kind of intensive out-patient treatment; it could turn out that you get revoked and sent to prison.
Consult with a local lawyer who has experience on DWI cases and the reputation of the interlock company in question. Some of those devices are super questionable; others are okay. Talk frankly with that lawyer about any reasons that you know that it may be failing. (BTW, everyone has heard the "mouthwash" excuse so forget that.)
Your question is focused on the interlock alone, but the judge is more likely to look at the larger picture. How are you doing generally with your rehab, abstinence and compliance with other requirements of your probation. Certainly, the court will want to know why the failure occurred. If it alcohol related, which is suggested by your question, the court's view will be more harsh, because it suggests that you are failing your efforts, if any, rehab your relationship with alcohol. Be prepared to show the court that you are seriously taking efforts to change your relationship with alcohol..