Description
OBD-II Trouble Code Description for P0405 Audi
Exhaust Gas Recirculation Sensor “A” Circuit Low
What does this mean?
OBD2 Code P0405 Audi definition:
There are different designs of EGR (Exhaust Gas Recirculation) systems, but they all operate in a similar way. The EGR valve is a PCM (Powertrain Control Module) controlled valve that allows measured amounts of exhaust gasses to pass back into the cylinders to be burned with the air/fuel mixture. Since exhaust gas is an inert gas that displaces oxygen, injecting it back into the cylinder can lower combustion temperatures which helps to improve NOx (oxides of nitrogen) emissions. EGR isn’t needed on cold startup or at idle. EGR is commanded on under certain conditions like startup or at idle. EGR is commanded on under certain conditions like partial throttle or decel depending on engine temperature and load, etc. Exhaust gasses are supplied to the EGR valve from an exhaust pipe or the EGR valve may be mounted directly in the exhaust manifold. When needed, the valve is commanded “on” allowing the gasses to pass into the cylinders. Some systems divert exhaust gasses directly into the cylinders while others simply inject it into the intake manifold where it is then pulled into the cylinders. while others simply inject it into the intake manifold where it is then pulled into the cylinders.
Some EGR systems are quite simple while others are a little more complicated. Electrically controlled EGR valves are directly controlled by the PCM. A wiring harness plugs into the valve itself and is commanded by the PCM as it sees the need. These can be 4 or 5 wire. Usually 1 or 2 grounds 12 volt ignition feed, a 5 volt reference circuit, and a feedback circuit. Other systems are vacuum controlled. These are quite simple. The PCM controls a vacuum solenoid which when activated, allows vacuum to travel to the EGR valve and open it. There should also be an electrical connector on this type of EGR valve for the feedback circuit. The EGR system feedback circuit allows the PCM to see if the EGR valve pintle is actually moving as it should. If the feedback circuit detects that the voltage is unusually low, or it’s position is lower than it’s commanded to be, P0405 Audi may set.
Symptoms
Possible sumptoms of OBD code P0405 Audi
MIL (Malfunction Indicator Lamp) illumination
Causes
Possible causes of OBD code P0405 Audi
Short to ground in EGR signal or Reference circuits
Short to voltage in EGR ground or signal circuits
Bad EGR valve
Bad PCM wiring issues due to chafing or loose terminals
Possible Solutions
If you have access to a scan tool you can command the EGR valve on. If it responds and the feedback indicates the valve is moving properly then the problem may be intermittent. Sometimes in cold weather, moisture can freeze in the valve causing it to stick. After the vehicle warms up the problem may disappear. Carbon or other debris can lodge in a valve causing it to stick also
If the EGR valve doesn’t respond to your commands with the scan tool, disconnect the EGR harness connector. Turn the key to on position, engine off (KOEO). Using a voltmeter, check for 5 volts on the reference wire to the EGR valve. If there is no 5 volts, is there any voltage at all? If there is 12 volts, then repair short to voltage in the 5 volt reference circuit. If there is no voltage connect a test light to battery voltage and probe the 5 volt reference wire. If the test light illuminates, the 5 volt reference circuit is shorted to ground. Repair as necessary. If the test light doesn’t illuminate check for an open in the 5 volt reference circuit. Repair as necessary
If there is no apparent problem and there is no 5 volt reference, PCM may be at fault, however other codes will likely be present. If 5 volts are present on the reference circuit, jumper the 5 volts to the EGR signal circuit. Now the EGR position on the scan tool should read 100 percent. If it doesn’t connect test light to battery voltage and probe the EGR signal circuit. If it illuminates, then the signal circuit is shorted to ground. Repair as necessary. If the light doesn’t illuminate, check for an open on the EGR signal circuit. Repair as necessary.
If, after jumpering the 5 volt reference circuit to the EGR signal circuit the scan tool EGR position reads 100 percent, then check for poor terminal tension at the EGR valve connector. If the wiring is okay, replace the EGR valve.
The OBD2 Code Information Be Applicable For Audi:
2013 Audi TT ultra quattro Concept,2013 Audi TT RS plus,2013 Audi TTS Roadster competition,2013 Audi TTS Coupe competition,2013 Audi Sport quattro Concept,2013 Audi SQ5 TDI,2013 Audi S8,2013 Audi S7 Sportback,2013 Audi S6 Avant,2013 Audi S6,2013 Audi S4 Avant,2013 Audi S4,2013 Audi RS5 DTM,2013 Audi RS4 Avant,2013 Audi R8 e-tron Concept,2013 Audi R8 V10 plus,2013 Audi R8 V10 Spyder,2013 Audi R8 V10,2013 Audi R8,2013 Audi Q5,2013 Audi Nanuk quattro Concept,2013 Audi A8 L Hybrid,2013 Audi A8 Hybrid,2013 Audi A6 allroad quattro,2013 Audi A6 Black Edition,2013 Audi A4 allroad quattro,2013 Audi A4 Avant,2013 Audi A4,2013 Audi A3 e-tron Concept,2013 Audi A3,2013 Audi A1 quattro,2012 Audi e-bike Worthersee Concept,2012 Audi S5 Sportback,2012 Audi S5 Cabriolet,2012 Audi S5,2012 Audi RS Q3 Concept,2012 Audi RS5,2012 Audi RS3 Sportback,2012 Audi R8 GT Spyder,2012 Audi R8 Exclusive Selection,2012 Audi Q5 Hybrid quattro,2012 Audi Q3 Vail Concept,2012 Audi Q3 Jinlong Yufeng Concept,2012 Audi Q3,2012 Audi Crosslane Coupe Concept,2012 Audi A8 L Security,2012 Audi A6 L e-tron Concept,2012 Audi A6 Hybrid,2012 Audi A6 Avant,2012 Audi A6,2012 Audi A5 Sportback,2012 Audi A5 DTM,2012 Audi A5 Coupe,2012 Audi A5 Cabriolet,2012 Audi A1 amplified,2012 Audi A1 Sportback,2011 Audi Urban Spyder Concept,2011 Audi Urban Concept,2011 Audi TT Roadster,2011 Audi TT Coupe,2011 Audi TTS Roadster,2011 Audi TTS Coupe,2011 Audi S5 Sportback,2011 Audi RS5,2011 Audi R8 Spyder 5.2 FSI quattro,2011 Audi R8 Spyder 4.2 FSI quattro,2011 Audi R8 GT,2011 Audi R18,2011 Audi Q7,2011 Audi A8 L,2011 Audi A8,2011 Audi A7 Sportback,2011 Audi A3 e-tron Concept,2011 Audi A3 Sportback,2011 Audi A3 Concept,2011 Audi A3 Cabriolet,2011 Audi A3,2011 Audi A2 Concept,2011 Audi A1 clubsport quattro Concept,2011 Audi A1,2010 Audi quattro Concept,2010 Audi e-tron Spyder Concept,2010 Audi e-tron Concept,2010 Audi TT RS Roadster,2010 Audi TT RS,2010 Audi TT GT4 Concept,2010 Audi S5 Cabriolet,2010 Audi R8 V10 5.2 FSI quattro,2010 Audi Q7,2010 Audi A8 Hybrid Concept,2010 Audi A5 Sportback,2010 Audi A5 Cabriolet,2010 Audi A4 allroad quattro,2010 Audi A1 e-tron Concept,2009 Audi e-tron Concept,2009 Audi TTS Roadster,2009 Audi TTS Coupe,2009 Audi Sportback Concept,2009 Audi S6 Avant,2009 Audi S6,2009 Audi S4 Avant,2009 Audi S4,2009 Audi S3 Sportback,2009 Audi S3,2009 Audi RS6,2009 Audi R8 GT3,2009 Audi Q7 V12 TDI,2009 Audi Q5 Custom Concept,2009 Audi Q5,2009 Audi A6 allroad quattro,2009 Audi A6 Avant,2009 Audi A6,2009 Audi A4 Avant,2009 Audi A4,2009 Audi A3 Sportback,2009 Audi A3,2008 Audi TT clubsport quattro Concept,2008 Audi TT Roadster 3.2 quattro,2008 Audi TT Coupe,2008 Audi S8,2008 Audi S6,2008 Audi S5,2008 Audi S4 Cabriolet,2008 Audi RS6 Avant UK Version,2008 Audi RS6 Avant,2008 Audi RS4 Cabriolet,2008 Audi RS4,2008 Audi R8 V12 TDI Concept,2008 Audi R8 TDI Le Mans Concept,2008 Audi R8,2008 Audi Q7,2008 Audi A8 L,2008 Audi A8 4.2 TDI quattro,2008 Audi A8L W12 quattro,2008 Audi A8,2008 Audi A6 Avant,2008 Audi A6,2008 Audi A5 3.0 TDI quattro,2008 Audi A5,2008 Audi A4 US Version,2008 Audi A4 TDI Concept e,2008 Audi A4 Cabriolet,2008 Audi A4,2008 Audi A3 US Version,2008 Audi A3 TDI clubsport quattro Concept,2008 Audi A3 Cabriolet,2008 Audi A1 Sportback Concept,2007 Audi metroproject quattro Concept,2007 Audi TT clubsport quattro Concept,2007 Audi TT Roadster 2.0 TFSI,2007 Audi TT Roadster,2007 Audi TT Coupe S-line,2007 Audi TT Coupe,2007 Audi S3,2007 Audi R8,2007 Audi Q7 V12 TDI Concept,2007 Audi Q7 V12 TDI,2007 Audi Cross Coupe quattro Concept,2007 Audi Cross Cabriolet quattro Concept,2006 Audi S8,2006 Audi S6 Avant,2006 Audi S6,2006 Audi S4 Cabriolet,2006 Audi Roadjet Concept,2006 Audi RS 4 Cabriolet,2006 Audi RS 4 Avant,2006 Audi RS4,2006 Audi Q7,2006 Audi A8 Security,2006 Audi A6 allroad quattro,2006 Audi A4 Cabriolet,2006 Audi A3 2.0T,2005 Audi allroad quattro V8 4.2,2005 Audi allroad quattro V6 2.7T,2005 Audi TT quattro sport,2005 Audi TT Roadster 3.2,2005 Audi TT Roadster 1.8T,2005 Audi TT Coupe 3.2,2005 Audi TT Coupe 1.8T,2005 Audi Shooting Brake Concept,2005 Audi S4 Cabriolet,2005 Audi S4 Avant,2005 Audi S4,2005 Audi RS4,2005 Audi Q7 Hybrid Concept,2005 Audi Allroad quattro Concept,2005 Audi A8 L W12,2005 Audi A8 L 4.2,2005 Audi A8 4.2 TDI quattro,2005 Audi A8 4.2,2005 Audi A8 3.2 FSI quattro,2005 Audi A8L 4.2 TDI quattro,2005 Audi A6 Avant,2005 Audi A6 4.2 quattro Sline,2005 Audi A6 3.2,2005 Audi A6 3.0 TDI quattro,2005 Audi A6L,2005 Audi A4 DTM Edition,2005 Audi A4 Cabriolet,2005 Audi A4 Avant 3.2 quattro,2005 Audi A4 3.2 quattro,2005 Audi A4 3.0 TDI quattro,2005 Audi A4 2.0T,2005 Audi A3 2.0 TDI 3-door,2004 Audi S4 Cabriolet,2004 Audi RSQ Concept,2004 Audi RS6 plus,2004 Audi A8 L 6.0 W12 quattro,2004 Audi A8 L 3.0 quattro,2004 Audi A8 4.2 quattro,2004 Audi A8 3.7 quattro,2004 Audi A8 3.0 TDI quattro,2004 Audi A8,2004 Audi A3 Sportback quattro,2004 Audi A3 Sportback S-line,2004 Audi A3 Sportback,2004 Audi A3 3-door,2003 Audi allroad quattro,2003 Audi TT Roadster 3.2 quattro,2003 Audi TT 3.2 DSG quattro,2003 Audi Pikes Peake quattro Concept,2003 Audi Nuvolari quattro Concept,2003 Audi Le Mans quattro Concept,2003 Audi A8 L 4.2 quattro,2003 Audi A8 4.0 TDI quattro,2003 Audi A4,2003 Audi A3 3.2 V6 3-door,2003 Audi A3 3-door,2003 Audi A2,2002 Audi allroad quattro 4.2,2002 Audi allroad quattro,2002 Audi TT Roadster,2002 Audi S6 Avant,2002 Audi S6,2002 Audi S4 Avant,2002 Audi S4,2002 Audi S3,2002 Audi RS6 Sedan,2002 Audi RS6 Avant,2002 Audi RS6,2002 Audi A6,2002 Audi A4 Cabriolet 3.0,2002 Audi A4 Cabriolet 2.4,2002 Audi A4 Cabriolet 1.8 T,2002 Audi A4 Cabriolet,2002 Audi A4 Avant,2002 Audi A4,2002 Audi A3 3-door,2002 Audi A2,2001 Audi TT Coupe,2001 Audi Avantissimo Concept,2001 Audi A8 L 6.0 quattro,2001 Audi A6 Avant,2001 Audi A6,2001 Audi A4 Avant,2001 Audi A4
Note:
1. The list of automotive Makes at the right edge of the screen. The currently selected ODB-ii codes is for the Audi makes.
2. Look up the other OBD II Trouble Codes, please use the search box. Enter the 5 character trouble codes in the search box and submit the search.
3. Don’t assume a particular OBD-II code means the same for other auto manufacturers as there are many makes specific codes in use.
4. If your OBD-II trouble codes are for a different car, select that vehicle series before searching for the diagnostic codes because not all OBD2 codes used by one manufacture are used by the other makes.
5. The information contained on this site is presented for informational purposes only. We are not responsible for any actions you take on your vehicle. If you have any doubt as to repairs on your vehicle, please contact your technician.