Jump to content
Ultimate Subaru Message Board

Recommended Posts

so the car started throwing a p0400 intermittently. it will stay on for a few
days and then mysteriously dissapear for about a day then come back. i have
disassembled, cleaned and reassembled the egr also replaced the vacuum valve
(circled below) any other suggestions or possible loose wires i should be
looking for?



Share this post

Link to post
Share on other sites

There is a vacuum solenoid under the number 4 intake runner that could be clogged or not working

Look under the dash and find the two green test mode plugs, connect them and turn the key ON. All of the relays and solenoids under the hood will start to click on and off. Put your finger on the EGR vacuum solenoid to see if it clicks. Connect a length of hose to one port and see if you can blow air through the solenoid while it is clicking on and off.

Air should flow then stop in unison with the clicking of the solenoid.

If no air flows the solenoid is clogged and needs to be replaced.

If the solenoid does not click it could be bad, you can check resistance of the solenoid, or look for voltage at the connector while in test more.

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now