chuck d.
New member
I have a 1999 Suburban with 160,000 miles. It recently needed a Calif. smog check. It passed the test with flying colors except the EGR system wasn't working properly. The MIL was NOT on. I brought the vehicle home and removed the EGR valve and cleaned carbon from a stuck valve. The valve now moved freely and I reinstalled it. I have an Actron scan tool and I should have used it before I took the vehicle in for the test but I didn't. I now plugged the scan tool in and it showed the P0404 (EGR) trouble code. I cleared the code and ran the vehicle for about 25 miles and the scan tool showed no new trouble codes. I then took the vehicle in for a retest. The tech plugged in his machine and it showed that 3 systems were NOT ready for testing. The systems were "catalyst", "evaporiyive system" and "secondary air system". The tech suggested that I drive the vehicle for 50 to 100 miles to reset the monitors. I drove it for over 100 miles with several stops and starts and took it back in. It still showed the same 3 systems not ready. I then drove in for another 120 miles with numerous stops and starts over a week. It still shows the 3 systems NOT ready. Does anyone know what it takes to reset these three systems? How many starts, stops etc. are needed?