I own a 1998 Nissan Quest GXE (3 doors, 3.0L), 275K mileage.
The "Service Engine Soon" light is on...
P0400 - Exhaust Gas Recirculation Flow Malfunction
P0325 - Knock Sensor Circuit (Bank 1)
Instead of taking this very reliable, running smoothly vehicle into the shop i wanted to take a stab at resolving the issue. I'm starting with the EGR issue.
Below are some images of the area. If i understand things correctly:
(A) & (W) = EGR Valve
(X) & (V) = EGR CONTROL-BPT VALVE
(Y) = Vacuum hose from the EGR Control Valve to the top part of the EGR Valve (near (W) but not shown).
(B) connects the bottom of the EGR Valve to the bottom of the EGR Control Valve
(C) connects the side of the EGR Valve to the exhaust manifold
(Z) = UNKNOWN
TROUBLESHOOTING
I have a manual vacuum pump. I attached it to the EGR Valve's vacuum line at the top of the unit then started the car. I then created a vacuum with the pump and noticed the car attempting to stall. My understanding is this test proves the EGR Valve is ok.
Moving backwards to the EGR Control, i have no clue on what to do next. The line between the EGR Valve and Control is a fixed metal line and so i can assume the line itself is fine. How do i test this EGR Control?
![]()
![]()
![]()
The "Service Engine Soon" light is on...
P0400 - Exhaust Gas Recirculation Flow Malfunction
P0325 - Knock Sensor Circuit (Bank 1)
Instead of taking this very reliable, running smoothly vehicle into the shop i wanted to take a stab at resolving the issue. I'm starting with the EGR issue.
Below are some images of the area. If i understand things correctly:
(A) & (W) = EGR Valve
(X) & (V) = EGR CONTROL-BPT VALVE
(Y) = Vacuum hose from the EGR Control Valve to the top part of the EGR Valve (near (W) but not shown).
(B) connects the bottom of the EGR Valve to the bottom of the EGR Control Valve
(C) connects the side of the EGR Valve to the exhaust manifold
(Z) = UNKNOWN
TROUBLESHOOTING
I have a manual vacuum pump. I attached it to the EGR Valve's vacuum line at the top of the unit then started the car. I then created a vacuum with the pump and noticed the car attempting to stall. My understanding is this test proves the EGR Valve is ok.
Moving backwards to the EGR Control, i have no clue on what to do next. The line between the EGR Valve and Control is a fixed metal line and so i can assume the line itself is fine. How do i test this EGR Control?
