P0404 Error Code

UPMM019

MEMBER
2001 CHEVROLET MONTE CARLO
3.8L
V6
FWD
AUTOMATIC
212,408 MILES

I just bought this car used it is a one owner vehicle and has 212,000 miles on it. Seems pretty clean for the age and the owner seemed to take care and service it, so he says.

No sooner did I buy it and drive it home the check engine light went on. The error code is P0404.

When I got the car and drove it home about an hour interstate it drove and rode great. It has a smooth idle.

I parked it and then went to the DMV, a few hours later I came back. The weather was turning to rain. When I started it it seemed a little rough and then when I pulled out on the main road the check engine when on and at the same time seemed sluggish.

I am wondering based upon code alone if I should be concerned? I think I have seen where the EGR valve can be cleaned or replaced and that solves the issue.

Looking for general troubleshooting guidance.

1 Reply

SATURNTECH9

MECHANIC
30,870 POSTS

The number one fix for that code on that car is to replace the egr valve. It sounds like the pintle is sticking open due to carbon build up. You can try cleaning it using a carbon cleaner. Also what I like to do is turn the valve upside down. Then push the pintle down letting it stick open. Then fill the area with carbon cleaner then let it soak. Then after that spin the pintle left to right while pushing the pintle up and down. That will help clean the shaft of the pintle. If it sticks again then you will have to replace it. Also start it without the egr valve on. Let it run a few seconds to help blow carbon out. It should rev up high rpms and have a loud exhaust leak sound. That means both egr ports are clear. Let me know how it goes.