I have a 99 Maxima with 100,600 miles on it. A couple of weeks ago (while it was still under warranty) the Service Engine Soon light came on. The code was P0400 - EGR Flow Malfunction. I took it to the dealer and they said the EGR system needed "cleaned out". Their estimate was $400. We bought a new EGR valve for only $120, put it on, cleared the code and everything was fine for a couple of days. Light came on again, same code. Took EGR valve off, used carb cleaner to clean the metal tube that connects to the EGR Valve and even took a brush to the tube in an attempt to clean it out. Put everything back together, cleared the ECU and car ran great. Couple of hours later, light came on again and it's still EGR Flow Malfunction.
We are at our wits end with this! Can anybody offer up a suggestion?
