Possible causes

– EGR volume control solenoid valve
– EGR volume control solenoid valve harness is open or shorted
– EGR volume control solenoid valve circuit poor electrical connection
– EGR temperature sensor and circuit

Tech notes

There is a factory service bulletin for the following Ford models:

2003-2007 Ford F-Super Duty
2004-2007 Ford E-350, E-450
2003-2005 Ford Excursion
Ford Factory Service Bulletin OBDII Code P0404

When is the code detected?

An improper voltage signal is sent to ECM through the valve

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)
– Engine hesitation

P0404 FORD Description

Early Exhaust Gas Recirculation (EGR) systems component s include and EGR Valve, and Engine Control