Recently bought a used Accord. Car has over 200k but drives great. The previous owner told us that it had code P401 (insufficient EGR flow). I used a scan tool to reset the code but it just comes right back. The EGR valve has been replaced. I went to clean the EGR ports but found out I have a F23a4 engine. It looks like the F23a4 intake does not have any EGR ports. Not sure if the engine was swapped in or not. The engine idles ruff and sometimes dies. What can I do to reset the code and clean out the EGR system?

 

It looks like I have to take the intake manifold completely apart according to this thread: https://honda-tech.com/forums/honda-accord-1990-2002-2/f23a4-ulev-2691467/

 

It looks like a few cars were sold with the ULEV engine which means you have to watch out for difference like intakes and wiring.