Code P0400, no EGR flow?

BLAZ85

MEMBER
2004 NISSAN XTERRA
3.3L
V6
4WD
AUTOMATIC
126,000 MILES

We have the above code on the vehicle listed above. My first question deals with the operation of the EGR system. Is the system active when the engine warms to operating temperature and the gear selector is in Park or Neutral? In other words, if the vehicle is in Park and revved to 2000 RPM's, should I have EGR flow? Or does the vehicle have to be in gear?
The second question deals with the vacuum solenoid that passes vacuum to the EGR valve. Does the ECM ground this solenoid to pass vacuum to the valve?
I intend to check the valve by using my vacuum pump to apply vacuum. If the valve is good and not clogged, it should cause the engine to stumble at idle. I will check the solenoid electrically. If both of these checks out okay, then it is probably going to be the EGR flow sensor (ouch!).
Any other words of wisdom concerning this code would be appreciated.
Thank you in advance for your reply.

2 Replies

KEN L

MASTER CERTIFIED MECHANIC
47,952 POSTS

I would check the valve and check the inlet and outlet ports to see if they are clogged with carbon. This video can help:

https://youtu.be/DqUCbbKdWf4

The ECM will ground the control solenoid to initiate its operation. The operation of the valve will vary depending on the conditions of the engine's operation determined by the ECM. Let us know what happens and please upload pictures or videos of the problem so we can see what's going on.