Volkswagen P0404 Exhaust Gas Recirculation Control Circuit Range/Performance

Description

OBD-II Trouble Code Description for P0404 Volkswagen

Exhaust Gas Recirculation Control Circuit Range/Performance

What does this mean?

OBD2 Code P0404 Volkswagen definition:
The EGR (Exhaust Gas Recirculation) system’s purpose is to redirect exhaust gas back into the cylinders. Since exhaust gas is inert, it displaces oxygen and fuel, thereby lowering cylinder temps, which, in turn, lowers oxides of nitrogen emissions. For that reason it needs to be carefully metered into the cylinders (via the EGR valve) so as not to adversely affect the engine’s performance. (Too much EGR and the engine won’t idle). If you have a P0404 Volkswagen, then the EGR valve is likely an electrically controlled EGR valve instead of a vacuum controlled EGR valve. Also, the valve will usually have a feedback system built into it that informs the PCM (Powertrain Control Module) what position the valve is in; open, closed, or somewhere in between. The PCM needs to know this to determine whether or not the valve is operating as needed. If the PCM determines that the valve should be operating, but the feedback circuit shows that the valve is not open, this code will set. Or if the PCM determines the valve should be closed but the feedback signal indicates that the valve is open, this code will set.

Symptoms

Possible sumptoms of OBD code P0404 Volkswagen
There may be no symptoms of a P0404 Volkswagen DTC other than the MIL (malfunction indicator lamp) or check engine light. However, Exhaust Gas Recirculation systems are inherently problematic due to carbon buildup in the intake manifold, etc. This normal buildup can lodge in an EGR valve, holding it open when it should be closed. If this is the case, the engine may idle rough, or not at all. If the valve has failed and is NOT opening, then symptoms would be higher combustion temps and as a result, higher Nox emissions. But the latter symptoms aren’t going to be noticeable to a driver.

Causes

Possible causes of OBD code P0404 Volkswagen
Usually this code points to either carbon buildup or a bad EGR valve. However that doesn’t rule out the following: Open or short in the 5 Volt reference circuit Open or short in the ground circuit Open or short in the PCM controlled voltage circuit Bad PCM (less likely)

Possible Solutions

Using a scan tool command the EGR valve to open while watching the actual EGR position (it will probably be labeled “desired EGR” or something similar). The actual EGR position should be very close to the “desired” EGR position. If it is, then the problem is likely intermittent. It may have been a lodged piece of carbon that has since dislodged, or it could be a bad EGR valve winding that intermittently opens or shorts as the valve temperature changes. If the EGR “desired” position is not close to the “actual” position, then unplug the EGR sensor. Check for a good 5 Volt reference voltage to the connector. If it doesn’t show a reference voltage, repair an open or short in the 5 Volt reference circuit. If there is a 5 volt reference voltage, activate the EGR with the scanner, monitor the EGR ground circuit with a DVOM (Digital Volt/Ohm meter). It should indicate a good ground. If it doesn’t then repair the ground circuit. If there is a good ground, then check the control circuit. It should indicate voltage that varies according to the percentage that the EGR is open. As it’s open more, the voltage should increase accordingly. If it does, then replace the EGR valve. If the voltage doesn’t increase incrementally, then repair open or short in EGR control circuit.

Related Codes

p-400 p0401 p0402 p0403


The OBD2 Code Information Be Applicable For Volkswagen:

2013 Volkswagen e-Co-Motion Concept,2013 Volkswagen Up 4-door,2013 Volkswagen Up,2013 Volkswagen Touareg Edition X,2013 Volkswagen Scirocco GTS,2013 Volkswagen Santana,2013 Volkswagen Polo R WRC,2013 Volkswagen Polo BlueGT,2013 Volkswagen Passat Alltrack,2013 Volkswagen Lavida,2013 Volkswagen Kombi Last Edition,2013 Volkswagen Jetta Hybrid,2013 Volkswagen Golf Sportsvan Concept,2013 Volkswagen Golf Plus Life,2013 Volkswagen Golf Mk VII UK-Version,2013 Volkswagen Golf GTI Cabriolet,2013 Volkswagen Golf,2013 Volkswagen Gol 2-door,2013 Volkswagen Eco Up,2013 Volkswagen Caddy Cross,2012 Volkswagen Tiguan,2012 Volkswagen Jetta GLI,2012 Volkswagen Beetle,2011 Volkswagen eT Concept,2011 Volkswagen e-Up Concept,2011 Volkswagen XL1 Concept,2011 Volkswagen Touran,2011 Volkswagen Touareg,2011 Volkswagen Sharan,2011 Volkswagen Polo GTI,2011 Volkswagen Phaeton,2011 Volkswagen Jetta,2011 Volkswagen Eos,2011 Volkswagen CrossTouran,2011 Volkswagen CrossPolo,2011 Volkswagen CrossGolf,2011 Volkswagen Amarok,2010 Volkswagen Polo,2010 Volkswagen Golf,2009 Volkswagen Phaeton,2009 Volkswagen Golf,2009 Volkswagen Gol,2008 Volkswagen Phaeton,2008 Volkswagen Golf Variant,2008 Volkswagen Golf GTI Concept,2008 Volkswagen Golf BlueMotion,2007 Volkswagen Up Concept,2007 Volkswagen Touran,2007 Volkswagen Touareg,2007 Volkswagen Eos,2006 Volkswagen Rabbit,2006 Volkswagen Passat,2006 Volkswagen Jetta,2006 Volkswagen Eos,2006 Volkswagen CrossPolo,2005 Volkswagen Touareg,2005 Volkswagen Golf,2005 Volkswagen Fox,2004 Volkswagen RaceTouareg,2004 Volkswagen Golf,2004 Volkswagen Concept T,2004 Volkswagen Concept C,2003 Volkswagen Touran,2003 Volkswagen Passat

 

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