thanks again for all of your help.I am using kts 540 with esi, please show me what you are seeing.In response to Chris's information, this is what I am seeing on my zafira-4.5 volts on pin 4, static voltage doesn't change with erg position, when I scoped this signal(feedback) I am seeing a duty cycle with no change in frequency when I am actuating the egr valve diagnostically.On live data I am seeing the same pids as you but, egr feedback shows incorrect using auto diagnose & g scan 2, but egr feedback ok when using bosch kts.....help