https://wiki.ross-tech.com/wiki/index.php?action=history&feed=atom&title=P20EE%2F008430 2026-05-25T03:40:45Z Revision history for this page on the wiki MediaWiki 1.43.3 https://wiki.ross-tech.com/wiki/index.php?title=P20EE/008430&diff=9773&oldid=prev 2025-09-15T19:06:34Z

<p>Created page with &quot;__FORCETOC__ == P20EE/008430 - SCR NOx Catalyst Bank 1: Efficiency too Low == == Possible Symptoms == * MIL (Malfunction Indicator Lamp) ON * Loss of power (limp mode) possi...&quot;</p> <p><b>New page</b></p><div>__FORCETOC__<br /> == P20EE/008430 - SCR NOx Catalyst Bank 1: Efficiency too Low ==<br /> <br /> <br /> == Possible Symptoms ==<br /> * MIL (Malfunction Indicator Lamp) ON<br /> * Loss of power (limp mode) possible<br /> * Increased emissions<br /> * DTC stored in ECM<br /> <br /> <br /> == Possible Causes ==<br /> * SCR NOx Catalyst efficiency below threshold<br /> * Faulty NOx sensor(s) (upstream or downstream)<br /> * Faulty Reducing Agent Injector -N474-<br /> * Reducing Agent (AdBlue®) quality concern<br /> * Incorrect dosing of reducing agent<br /> * Exhaust leaks upstream of SCR Catalyst<br /> * Catalyst temperature not within range<br /> * DPF regeneration status interfering with monitoring<br /> <br /> <br /> == Possible Solutions ==<br /> * If a NOx sensor DTC is also present, diagnose that DTC first<br /> * Check Reducing Agent (AdBlue®) quality <br /> * Check NOx Sensor Control Modules <br /> * Check Reducing Agent Injector -N474- https://forums.ross-tech.com/index.php?threads/18568/ <br /> * Inspect for exhaust leaks before SCR catalyst<br /> * Verify AdBlue system operation and dosing<br /> * Perform basic settings / adaptations as per factory repair manual<br /> * Replace SCR catalyst if efficiency cannot be restored<br /> <br /> <br /> == Special Notes ==<br /> * Criteria for Monitoring (as per the offical rapair manuals)<br /> ** Difference between calculated and measured efficiency &gt; 0.3 [-]<br /> ** Status NOx sensor downstream = ready<br /> ** Status NOx sensor upstream = ready<br /> ** Urea dosing = active<br /> ** Adaptation = not active<br /> ** DPF regeneration = not active<br /> ** SCR Catalyst temp gradient &lt; 0.2 – 0.34 K/s<br /> ** SCR catalyst modeled temp = 240 – 350 °C<br /> ** NOx concentration upstream &lt; 1,500 ppm<br /> ** Integrated NOx mass flow upstream ≥ 0.4 g<br /> * If AdBlue® is contaminated or incorrect concentration, system performance may be affected. Always use fresh, correct specification AdBlue®.<br /> * If conditions for monitoring are not met (temperature, regeneration status, etc.), efficiency check may not run.</div>

Peter