Description
OBD-II Trouble Code Description for P0143 Audi
O2 Sensor Circuit Low Voltage
What does this mean?
OBD2 Code P0143 Audi definition:
The Catalytic Converter is used to help control emissions. The PCM (Powertrain Control Module) uses the signal from the oxygen sensor to the rear of the catalyst to monitor the catalyst’s efficiency. This is the bank 1,3 sensor. It’s a four wire sensor being supplied a 0.5 volt reference voltage as well as a power and ground circuit for the o2 sensor heater element. There is also a signal wire from the oxygen sensor to the PCM that can vary between about 0.1 volts to about 0.9 volts according to oxygen content of the exhaust. A properly working post-cat sensor will exhibit small changes at a slower rate than front o2 sensors. To over simplify: a post-cat sensor’s main job is to monitor catalyst efficiency, not control fuel management (although they can have a measure of influence over the front o2 sensor’s operation). If the PCM determines that the post-cat o2 sensor signal voltage is below a certain threshold for too long, P0143 Audi will set. PCM detected the HO2S signal was less than 156 mv for 28 seconds.
Symptoms
Possible sumptoms of OBD code P0143 Audi
Usually rear o2 sensor problems won’t cause drivability issues since they are an input that measures catalyst efficiency (unlike front o2 sensors). However if you have other codes present, like lean codes or pre-o2 sensor codes, then they may cause drivability problems as well as P0143 Audi. The following symptoms may be present: MIL (Malfunction Indicator Lamp) illumination Engine performance issues Engine running rough Engine running rich Poor idle
Causes
Possible causes of OBD code P0143 Audi
An engine that is running lean could set this code, however there will likely be other codes present. Air leaks in exhaust in front of o2 sensor giving false reading O2 sensor connector damaged O2 sensor signal circuit is shorted to ground O2 sensor ground circuit is open O2 sensor has failed (it may be contaminated with fuel or coolant) PCM has failed
Possible Solutions
It’s always good to start with checking for air leaks in the exhaust manifold and in the exhaust pipes. With KOER (Key on engine running) use a scan tool or a voltmeter check the o2 sensor signal voltage with engine warm. You may have to increase the RPM to a fast idle to check the voltage of the bank 1,3 sensor. If it’s voltage is stuck low (less than a half a volt) and you don’t have any other o2 sensor codes present in the PCM, then it’s a good bet that the sensor is bad. If the voltage isn’t stuck low and the o2 sensor seems to be operating fine, it’s likely sticking low intermittently. This often turns out to be the sensor. Having said that, if you’re interested in knowing for sure what the problem is then perform the following: 1. Turn off the engine and unplug the 1,3 o2 sensor connector. Make sure that there is battery voltage present and ground present for the o2 sensor heater. If there isn’t then diagnose that first then retest. If that checks out then, using a jumper wire, supply a chassis ground to the o2 sensor connector(PCM side) ground circuit. Now observe the scan tool bank 1,3 o2 sensor reading. If it is now at about a half a volt then replace the o2 sensor. If, after supplying a ground to the unplugged PCM side of the o2 sensor connector, the voltage reading doesn’t change then check the harness for short to ground. Check for harness making contact with exhaust components. Check pins for damage, and for moisture. Repair as necessary. If you can find no harness problems, then the PCM may be bad.
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
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