P0401 Code of Bad EGR Valve
 

1998 Acura CL. The code of P0401 said bad EGR valve. We've replaced the EGR valve, Check engine light back on. Got another EGR valve and replaced the newer one again. Check engine light came back on. Then did some checking and replaced the map sensor and the check engine light came back on after two weeks Checked the code and it's the same code: P0401, bad EGR valve. Getting very frustrated at this point. Please help. It's strange that it was fine and then after two weeks, the light comes back on and it's the same code.

You have the 6-cylinder engine, right? You're going to have to take the intake manifold off and clean out the EGR port (which is likely caked with carbon). Mine was pretty bad when I did it. I also replaced the intake manifold gasket at the same time. Valve clatter on acceleration went away, and fuel mileage improved. I will send some links to vids to give you a better idea of what needs to be done. It does involve taking apart the top end of the engine (but it's a good idea to give the intake a thorough cleaning all the way through every now and again.)

(Part 1 - P0401 Code) (Part 2 - P0401 Code) (Part 3 - P0401 Code)
(Another Youtube video explaining P0401 remediation)
(Scotty Kilmer - Same engine you have - J30 series 6 cyl) -
My advice: ALWAYS *replace* your gaskets! Don't re-use the old one. If you're going to the trouble of taking things apart to clean passages, consider how much trouble it is and whether it's really worth it or not to do it all over again just because you didn't replace the seal when you had the chance the first time. When in doubt, swap it out!