#Diesel# P0404 EGR Circuit Range/Performance (New EGR) #MAF Engine#

The vehicle lacks of power.

When I clear the p0404 fault code, the vehicle runs great for a couple of days or miles
(costumer mentioned that if he drove the car for big trips such as 100 miles or 150 miles the check engine comes on)

The vehicle has a 5 wire EGR valve.

For a start, I tried to identify my circuit design
because I wanted to manually energize the EGR to check for clogged passages.

(I don't have a scan tool that allows me to do output control tests)

I know on a 5 wire EGR, the 3 wires is for the potentiometer and the other 2 wires for the solenoid.

Key On Engine Off

EGR plugged in, backprobing

EGR Position sensor
Wire 1: 5v reference
Wire 2: 0.5v signal
Wire 3: 0v ground

EGR Solenoid
Wire 4: 1.6volts (bias voltage?)
Wire 5: 1.6volts (bias voltage?)

Now I realize that there's something wrong on the EGR Solenoid wires.

I was expecting to see
for a ground side switch a 12volts and 12volts and
for a power side switch a 0volts and 0volts.

Looks like a bias voltage on both wires?
Both wires read the same unplugged.

Whats the the year make model of vehicle? Have you checked circuit integrity to pcm? Bare wires etc...

UK Isuzu D-Max 2006

I don't have access on wiring diagram for this model.