How often does the interlock need to be monitored? Help Center › Category: General Support › How often does the interlock need to be monitored? 1 Vote Up Vote Down Paul Klenner How often does the interlock need to be monitored? 1 Answers 1 Vote Up Vote Down Best Answer IDNJ Support Staff The monitoring time interval can vary from state to state, but in New Jersey the interlock is monitored at the service center no more than every eight (8) weeks. This monitoring and calibration check will take approximately fifteen (15) minutes.