Originally Posted by
X-fired
I know this thread is ancient but I'm hoping some of you are still on here.
I also have had the CEL on due to a P0400 code so I replaced the EGR valve but the P0400 persists after clearing the codes.
I'm wondering if this can be caused by a leaky hose (mine look to be in fine condition) or an O2 sensor.
How many miles on the car? THat code is most usually an indication of little or no flow. WHat did the passages look like when you change the valve?
Is there 12 volts on one pin? If the ECU is telling it to open, you will have 12 volts on one side and zero on the other. IF you have zero on both sides, the B+ feed to it is not there, ya gotta fix that.
If you have 12 on both sides, you have good power but the ECU (at that particular time) is not asking it to open.