Checked Cam Sensor Retard using Car Scanner (android, free) on my 2001 Blazer today against Dash Command, Car Diagnostic Pro, and Vident hand-held scanner. Used VEEPAK bluetooth OBD2 interface. All agreed, at least for the 2001 V6 engine. App appears to check/clear codes on multiple vehicle systems. Maybe a useful tool. Note that I still doubt it will do CS retard on 1996-97 v6 based on my understanding of differences in PIDs. Likewise, V8 accuracy is unknown but who knows. Someone needs to check it against established scanners that has those vehicles. I suspect it is fine for 1998-2004 Blazers.