Question:

I have this P0400 EGR malfunction on my 1999 Nissan Maxima and reading ATS past newsletters, I have tested the egr valve and checked the integrity of the vacuum hoses and egr passages. However, after resetting the code, it came back after 1 week of driving. How do you fix this code? Is it possible that the ecm (engine computer) is defective?

ATS Adviser:

Base on your egr test, the ecm should be good but it is possible that you have not really cleaned the egr passages properly because this job requires the removal of the top plenum in your engine. Under this plenum contains a passage that is blocked and will result in an egr fault code. This can be tested by running your engine at idle and lifting the egr pintle shaft of the egr valve with your finger. When you do this, it should make your engine stall, if not, the passage itself is blocked.

ATS Tip:

While you do this, you can also test the egr valve which could be stuck closed including measuring the egr temperature sensor voltage. Finally, a bad battery can also cause this code which is known to occur. Contact ATS for more info.

This entry was posted on Wednesday, January 24th, 2007 at 5:52 am and is filed under Check Engine Light FIXES. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.