Egr flow malfunction P0400 Where do I begin?

[ImprezRS]

Check engine light came on, got the code read, P0400 - Egr flow Malfunction.

I am looking for others who have had the same problem and fixed it, or others who have advice. It's a 98 impreza rs. Thanks for the help.

ed

[99obw]

I would start by checking the backpressure transducer. If you search the board you might find me saying something about when I had this problem on our '99. I can't take the time to explain right now, must run to a meeting.

[color-blind]

  ImprezRS said:

Check engine light came on, got the code read, P0400 - Egr flow Malfunction.

I am looking for others who have had the same problem and fixed it, or others who have advice. It's a 98 impreza rs. Thanks for the help.

ed

 

You need a vacuum pump in order to check the system. First apply vacuum to egr valve-engine not running-it should be able to hold a vacuum. If not replace the valve-yet usually the egr valves do not fail. Then start the engine-at idle apply vacuum to the valve. The car should die or idle very rough. If it does not you have plugged passages and will need to remove the egr valve and clean the ports. Then inspect the metal tube that comes off of the valve-it should be clean and not plugged with carbon. If the tube is plugged clean it. If all the above check good then replace the egr transducer.

The above is the most common problems. Their are some other problems yet they are rare. Good luck.

[99obw]

Here is the thread I was thinking of....

 

http://www.ultimatesubaru.org/forum/showthread.php?t=8171&highlight=p0400