i have deleted the faults and advised customer to drive it a couple of days and bring it back ecu is dec 30 and engine code is z17dth it has done 138.000 miles when i drove the car it felt normal and had a good pull only the idle hunts between 850-900rpm and the mil is on. i will have a better look at it when it comes back. what is the best way to test the egr system? and where is it? thanks for your repplies