DTC Advanced Diagnostics: P0404

DTC P0404:Exhaust Gas Recirculation (EGR) Valve Circuit Range/Performance Problem

General Description

The exhaust gas recirculation (EGR) valve, which is controlled by the powertrain control module (PCM), is opened and the exhaust gas flows through the EGR valve, the intake manifold, and the EGR passage. The exhaust gas is circulated into the air/fuel mixture and the mixture is drawn into the combustion chamber to lower combustion temperatures, thus reducing oxides of nitrogen (NOx) emissions. A sensor (lift sensor) is built into the EGR valve and detects the amount of valve lift. The command value for the target valve lift is stored in the PCM so that exhaust gas recirculation can be optimized according to driving conditions. Comparing this command value with the lift sensor output signal value, the PCM controls the EGR valve to make the amount of actual valve lift equal to the command value. If the difference between the value of commanded EGR valve lift and actual EGR valve lift is a specified value or more, an abnormality in the EGR valve or the lift sensor output is determined, the PCM detects a malfunction and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type

Execution	Once per driving cycle
Sequence	None
Duration	5.0 seconds or more
DTC Type	Two drive cycles, MIL on

Enable Conditions

Condition	Minimum	Maximum
Engine speed [ENGINE SPEED]	–	5,500 rpm
Commanded EGR valve lift	0.010 in (0.25 mm)	–
12 volt battery voltage [BATTERY]	10.5 V	–

[ ]: HDS Parameter

Malfunction Threshold

The difference between the command value of the amount of EGR valve lift in the PCM and the actual amount of valve lift is 0.041 in (1.02 mm) or more for at least 5.0 seconds.

Possible Cause

NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.

	EGR valve response delay
	EGR valve full open stuck
	EGR valve middle stuck
	EGR valve position sensor line open
	EGR valve position sensor line short
	EGR valve position sensor middle stuck
	EGR valve position sensor range/performance problem

Confirmation Procedure

Operating Condition

1.	Start the engine. Hold the engine speed [ENGINE SPEED] at 3,000 rpm without load (CVT in P or N, M/T in neutral) until the radiator fan comes on.
2.	Drive the vehicle at a speed between 15 - 75 mph (24 - 120 km/h) for at least 5 seconds.

Drive the vehicle in this manner only if the traffic regulations and ambient conditions allow.

With the HDS

Do the EGR TEST in the INSPECTION MENU with the HDS.

Diagnosis Details

Conditions for setting the DTC

When a malfunction is detected during the first drive cycle, a Pending DTC is stored in the PCM memory. If the malfunction returns in the next (second) drive cycle, the MIL comes on and a Confirmed DTC and the freeze data are stored.

Conditions for clearing the DTC

The MIL is cleared if the malfunction does not return in three consecutive trips in which the diagnostic runs. The MIL, the Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command or by disconnecting the 12 volt battery.