EGR system cleaned but check engine light still comes on

I have a 2012 gen 3 with 271,000 miles and the check engine light came on. I watched all the videos and have read all the posts about P0401 code (wish I had read 170,000 miles ago). The car has been using a qt of 0-20w about every 1,000 miles. I cleaned the intake manifold, throttle body and the sensor beside the throttle body, maf sensor, egr pipe, valve and cooler. I changed the coolant, pcv valve and plugs since everything was taken apart. After reinstalling everything the check engine light keeps coming back on with the same p0401 code. I have had the codes cleared twice and even unhook the battery 7 or 8 times. I checked the gas cap too. The check engine light seems to come back on around 80 to 120 miles after I clear the code. I did replace the 12 volt battery about a month ago but still original traction battery.

 

The cooler was completely stopped up and I used the drill and wire to get through all the passages. It's not 100% clean, still a little build up in there but can see through it. Yes I did clean the inlet passages on the manifold. The mpg have dropped off from 43-45 to 37-40. Not sure what your talking about the plug on the egr valve. The black cap with the electric plug-in is seated all the way flush against the housing. The round cylinder inside that screws on though I'm not sure. I've put it back tight and loose and neither one has worked. I read where one guy put a washer in there because the little nub on the plastic inside was wore but that seems like it would just hold the valve open. I did mark the round cylinder and the little nub faces down when tight and does not touch the tit sticking out of the washer holding the spring on the valve itself.

 

Yes, I made sure the plunger moved freely up and down. When I cleaned that part I even made sure it was seating and not letting any cleaner come out until I pushed the plunger in. The wiring harness all look good but I have not checked fuses. I will do that this afternoon.

 

Yes, I made sure the plunger was free and I also made sure it was not leaking in the close position while I was cleaning it. The wiring harness seems ok and I will check fuses this afternoon. Thanks for the help.

 

Sorry for 2 posts but now I think I understand what plug on the egr valve you mentioned. I did unplug the connector and plug it back in to make sure it is seated good.

 

I made it about 140 miles today before the check engine light came back on.

 

Checked all the fuses and they are good.

 

I found that if I left something unplugged the check engine light was on right away. Sorry I cant help too much because I have not figured mine out yet.

 

Checked resistance on egr valve and all is good. Replaced map sensor and check engine light is still coming on. Any ideas anybody???

 

Thanks Mendel Leisk, I have been thinking about finding another used egr valve and cooler and redo everything.

 

I replaced the 12v battery a couple of months ago and we don't have to check emissions where I live so not sure about the catalytic converter. The only code it keeps showing is the p0401.

 

I ordered a used egr valve and cooler. After I clean them up and install maybe it will fix the problem. I'm thinking it's a bad egr valve at this point.

 

Yes, I sprayed brake cleaner inside of it while the plunger was open and shook it around to clean inside. I also sprayed more after it was cleaned and let go of the plunger to make sure the plunger was sealing good. After that I pushed the plunger back and forth to make sure it was not sticking. I have also taken it off about 6 more times since and tried to make sure it was not sticking.