My engine light came on about 3 months ago. I've been driving fine ever since-- no issues at all. the computer spits on a reading:

P0401 Exhaust Gas Recirculation (EGR) Insufficient Flow

We changed the EGR valve but the light just came back on even after restting the code-- what code it be?

 

I had same problem with my 98 ACURA SLX, and suspect that I wasted the better part of $200.00 replacing the valve and gasket when there was probably just too many deposits in the inlet or outlet hole. I am not a mechanic, but this is how I cleared the code. I removed the new EGR valve and Gasket, which exposes the inlet and outlet holes. With a COLD engine, I sprayed CRC carberator cleaner in the holes. I would spray a little directly into one hole and immediately wipe up what came out with a paper towel. Then I moved to the other hole and did the same thing. I repeated this about 10 times. Then I re-sprayed both holes without mopping it out and let the CRC cleaner sit for 15 minutes. I then started the ACURA (with the EGR valve still removed) to blow all the CRC out of the valve attachment housing. The vehicle hesitated, but started; and I pressed the accelerator several times to ensure all the cleaner was blown out. I then shut the engine off. I observed a small wisp of exhaust smoke swirling out the larger hole, so I knew that side was clear. I wiped the area up... re-installed the EGR... cleared the code with my OBD-II and started the ACURA. The fault never came back--and the engine runs like new. Good Luck

 

i had the same problem. i replaced my egr valve and solenioid and the fault kept coming back. the ports for the egr in the intake were clogged with carbon. you need to remove the caps and drill out the carbon build up in the intake and install new caps. if you can't do this bring it to honda it takes a couple of hours. this fixed my car and its common on the h22.