Code P0401 Insufficent EGR Flow Repair on 1998 Acura 3.5 RL

There are several things that can cause this code but generally it is a blocked port on the intake.  Before replacing any parts on this engine, you should clean out the port and EGR tube.  This is not a dificult thing to do but it is a tight spot to work in. 

(1) Remove the strut brace from top of the engine 2 12mm bolts at Cowl and four 12mm nuts 2 on each shock tower.(2) Remove EGR Valve 2 12mm nuts, one vacumn hose and one wire connector.

(3) Next remove the EGR Tube. It is hard to show in a picture but it is between the fire wall and the EGR Plate right below where the EGR mounts. It is held on by 2 10mm bolts on the EGR end. The other end runs over to the drivers side of the engine and is held on by 2 10 mm nuts. I used a 1/4 ratchet and short socket for the bolts on EGR side and added a 4"x 1/4 inch extension for the drivers side.

(4) After you have the tube removed you will need to inspect it and the EGR Valve for carbon build up and clean as required.  They may not be very dirty and they are probably not the problem causing this code. 

(5) Where the tube bolts on the drivers side rear of the engine is where you will find the restriction.  You will need a 1/4" and a 1/2" drill bit to clear the passage where the tube mounts. Start with the 1/4" drill bit and twist it straight in the hole towards the front of the engine by hand, it should go in the hole aproximately 2 1/2 inches and may be difficult because of the carbon build up.  After you have done this follow up with the 1/2" drill bit the same way. 

(6) Using compressed air remove the hose from the pvc valve located on the drivers side valve cover and blow through it to remove the carbon you have broken loose.

(7) Install everything back in reverse order and clear your codes. Drive your vehicle down the road at 55 to 60 mph and decelerate a few times.  You should do this for two complete drive cycles. 

(8) Congratulations you just saved yourself 400-500.00 for less than an hours worth of work and you will not get code P0401 for many miles to come.