Error awareness has been argued to depend on sensory feedback and interoceptive awareness (IA) (Ullsperger, Harsay, Wessel, & Ridderinkhof, 2010). We recorded EEG while participants performed a speeded Go/No-Go task in which they signaled error commission. Visibility of the effector was manipulated, while IA was measured with a heartbeat perception task. The late Pe was larger for aware than unaware errors. The ERN was also found to be modulated by error awareness, but only when the hand was visible, suggesting that its sensitivity to error awareness depends on the availability of visual sensory feedback. Only when the response hand was visible, the late Pe amplitude to aware errors correlated with IA, suggesting that sensory feedback and IA synergistically contribute to the emergence of error awareness. These findings underscore the idea that several sources of information accumulate in time following action execution in order to enable errors to break through and reach awareness.