As title states check engine light came on with 175k. First check engine light so she is s pleased. Checked freeze frame and voltage is low on cylinder 4 injector so without tear down I was going to order all 6 injectors at 120 a piece but she wants it torn down first. I have been told to throw one used injector in,but the amount of work to get to that particular injector, I might as well replace all of them since all 6 have to be removed. Mechanic recommended timing chain and 6 injectors from Amazon the are no name and cost less for 6 injectors than 1 AC Delco. I also gave her price for 6 spark plugs since intake plenum will be off and never changed. Question is, would you replace only bad one or all 6? All this while she states car can't be down more than a day.