I have a 97 accord and keep getting P0401 EGR flow insufficient. I removed the EGR valve and checked it. It was frozen shut so I replaced it figuring that was it. The same code was set after about 2 days of driving. I do not have a factory service manual so I don't know how it gets its signal that it is insufficient. I checked the lift sensor and it is recieving its 5 volt signal and I checked the vacuum hoses and they are fine. The soleniod that controls the vacuum actuates when I hook up voltage to it. My only thought is that the soleniod is not getting powered up and not letting the vacuum operate the EGR valve. So from the print I have from a chiltons it looks like it recieves its power to activate that solenoid from the ECM. Any ideas on how to check that? I also hooked up a vacuum pump directly to the EGR valve and activated it while running to see if the idle was affected and it was so I am pretty sure it has something to do with the computer but if anybody out there has a factory service manual with the procedure on how to check that particular function I would appreciate it.