Using various junction space-charge techniques, annealing, and simulation, a metastable defect in 6H SiC have been characterized. We suggest a configuration coordinate diagram with three configurations, where two of them can only exist when the defect is occupied by one or more electrons. The thermal ionization energies for the different configurations were measured and the thermal barriers for two of the transitions have been determined. It is also shown that the transformation process is governed by electron capturing to the defect.