P20EE - SCR NOx Catalyst Efficiency Below Threshold Bank 1

Repair Importance Level: 3/3
Repair Difficulty Level: 3/3  What does this mean?

Possible causes

  • Faulty NOx Sensor
  • Diesel Exhaust Fluid
  • Faulty Selective Catalyst Reduction (SCR) Catalyst

Possible symptoms

  • Engine Light ON (or Service Engine Soon Warning Light)

P20ee Description

The Selective Catalyst Reduction (SCR) catalyst is monitored to ensure it is capable of NOx conversion. The concentration of NOx upstream of the SCR is calculated based on a model. NOx concentration downstream of the SCR is measured with a NOx sensor. Using these concentrations, the cumulative efficiency of the SCR catalyst is calculated and compared to a threshold. If the cumulative efficiency is below this threshold for a sufficient period of time, a fault will be indicated.

The reductant, Diesel Exhaust Fluid (DEF), which is used as part of the SCR catalyst reaction, is monitored to ensure the tank is not refilled with an improper reductant. Upon detection of a refill event, the monitor is activated. After the SCR Catalyst Efficiency Monitor has completed and the SCR has been determined to be functional, the efficiency monitor continues to calculate the cumulative efficiency of the system. Each subsequent value for cumulative efficiency is included in two filtering routines, one for short term efficiency and the other for long term efficiency. If the difference between the two filtered efficiencies becomes greater than a threshold, a fault is indicated. the short term efficiency needs to be less than 0.20 and the delta between short and long term efficiency needs to be greater than 0.10.

OBDII Code P20ee - SCR NOx Catalyst Efficiency Below Threshold Bank 1 - Engine-Codes.com

P20EE Information for specific makes

P20EE CHEVROLET SCR NOx Catalyst Efficiency Below Threshold Bank 1
P20EE DODGE SCR NOx Catalyst Efficiency Below Threshold Bank 1   
P20EE FORD SCR NOx Catalyst Efficiency Below Threshold Bank 1
P20EE GMC SCR NOx Catalyst Efficiency Below Threshold Bank 1
Repair Importance Level: 3
1=Low 2=Medium 3=High  
Repair Difficulty Level: 3
1=Easy 2=Moderate 3=Hard  
Browse All Codes For Specific Model YearBeta
Ford F150 1998 Ford F150
1999 Ford F150
2000 Ford F150
2001 Ford F150
2002 Ford F150
2003 Ford F150
Ford Fusion 2006 Ford Fusion
2007 Ford Fusion
2008 Ford Fusion
2009 Ford Fusion
2010 Ford Fusion
2011 Ford Fusion
2012 Ford Fusion
Honda Accord 2008 Honda Accord
2009 Honda Accord
2010 Honda Accord
Honda Civic 1996 Honda Civic
1997 Honda Civic
1998 Honda Civic
1999 Honda Civic
2000 Honda Civic
Infiniti G35 2003 Infiniti G35
2004 Infiniti G35
2005 Infiniti G35
2006 Infiniti G35
Nissan Altima 2002 Nissan Altima
2003 Nissan Altima
2004 Nissan Altima
2005 Nissan Altima
2006 Nissan Altima
2008 Nissan Altima
2009 Nissan Altima
2010 Nissan Altima
2011 Nissan Altima
2012 Nissan Altima
Nissan Maxima 2005 Nissan Maxima
2006 Nissan Maxima
2007 Nissan Maxima
2008 Nissan Maxima
Nissan Pathfinder 2005 Nissan Pathfinder
2006 Nissan Pathfinder
2007 Nissan Pathfinder
2008 Nissan Pathfinder
2009 Nissan Pathfinder
2010 Nissan Pathfinder
2011 Nissan Pathfinder
2012 Nissan Pathfinder
Nissan Rogue 2008 Nissan Rogue
2009 Nissan Rogue
2010 Nissan Rogue
2011 Nissan Rogue
2012 Nissan Rogue
2013 Nissan Rogue
Nissan Sentra 2002 Nissan Sentra
2003 Nissan Sentra
2004 Nissan Sentra
2005 Nissan Sentra
2006 Nissan Sentra
2007 Nissan Sentra
2008 Nissan Sentra
2009 Nissan Sentra
2010 Nissan Sentra
2011 Nissan Sentra
2012 Nissan Sentra
Toyota Camry 1997 Toyota Camry
1998 Toyota Camry
1999 Toyota Camry
2000 Toyota Camry
2001 Toyota Camry
2006 Toyota Camry
2007 Toyota Camry
2008 Toyota Camry
2009 Toyota Camry
2010 Toyota Camry
2011 Toyota Camry
Toyota Corolla 2005 Toyota Corolla
Toyota Highlander 2001 Toyota Highlander
2002 Toyota Highlander
2003 Toyota Highlander
2004 Toyota Highlander
2005 Toyota Highlander
2006 Toyota Highlander
2007 Toyota Highlander
Toyota Prius 2004 Toyota Prius
2005 Toyota Prius
2006 Toyota Prius
2007 Toyota Prius
2008 Toyota Prius
2009 Toyota Prius
Scion xB 2005 Scion xB
2006 Scion xB
2007 Scion xB