2000 Nissan Altima OBD II code P0400

Question

My wife says the Service Engine Soon light will be on for a while (days, weeks) and then will go out (days, weeks) and will come back on. She hasn't noticed any driving differences and I don't drive it enough to notice. Where do you recommend starting?

Answer 1

Most likely the EGR and its pipes are clogged with carbon build. Cleaning is the first thing to do if you dont want to spend money replacing the part.