Impaired deficit awareness is common following traumatic brain injury (TBI) and is a major obstacle to rehabilitation. We have previously confirmed the presence of impaired error awareness in TBI using a highly discriminating go/no-go procedure. In the present study, we extend this work to try to identify more closely the nature of the error awareness deficit using measures of electrodermal activity (EDA). Sixteen participants with TBI and sixteen age-, sex-, and education-matched controls performed the Sustained Attention to Response Task (SART), while EDA was recorded. TBI detected significantly fewer errors compared to controls. EDA was significantly attenuated for TBI participants even to errors of which they were aware; error detection rates and EDA amplitude were also correlated. These findings suggest that poor insight following TBI may result, in part, from impaired error processing abilities.