I have a 1998 Accord V6 with P0401 & P1491 engine codes. I cleaned out the EGR clogged passage under the intake manifold. I'm still getting the P1491 code, but the P0401 code is gone. I was just wondering if anyone had experienced this & also if replacing the EGR valve & fixed the problem.



Is there an EGR test procedure somewhere? Thanks, Dean

 

Did you remove and clean the EGR valve and clean the passages below where the valve sits that lead up to the EGR rail and ports? Those passages are large but can get pretty sooty just like the upper ports and passages. If your ports were extremely clogged almost to where the soot was pushing up on the gasket and cover, definitely have a look at the rest of the EGR system. Extremely clogged ports means the valve itself is sooted up bad. On the bottom of that valve there is a little pintle that has to have free movement to allow and block the flow.

With engine running, take the hose off your EGR valve and hook a hand vacuum to the pipe on the valve and pump in about 8 inches of vacuum. The engine should stall and the EGR valve should hold the vacuum by itself until you take off the hose.

If everything is clean and you believe your EGR to be in working order, you might try clearing the code and driving the car until you can get the EGR valve to open normally, a nice cruise on a long stretch of highway should do it, and perhaps that will prevent the code from coming back. I mean the EGR system might just need to do its thing one time in order to be happy with the changes you made in cleaning the ports.

 

p1491 insufficient valve lift. you may have cleared the passages enough to allow some flow and solved the p0401, but your valve may not be lifting enough and still setting a p1491. probably the EGR valve, but you can't tell for sure unless you have a scan tool or another means of viewing the lift values and comparing to proper values. You may want to just try a used Valve or go ahead and buy a new one. you will probably spend more on diagnosis than the cost of the valve, unless you are a diagnostic tech. i assume you are not since you posted this.

 

I have th exact issue, I have P1491 on 96 Accord LX ( 2.2 lts , 4 cylinder), I did cleaned the intake ports and the code went away for 3 months, came back again, I have inspected the port , they are clean, measured vacuum as well, and found no apparant leak in tubing. changed the EGR with new one(think it must be sensor), but stil has the code , what else should be tried?