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.

 

How many miles on your car??

If your car has less than 150000 miles. Take it to your Honda dealerships. You have an Emission warrenty of 150000 miles.