Land rover dtc p249d 00. [P20EE-04] Selective Catalyst Reduction NOx Catalyst Efficiency Below Threshold - Bank 1 - System Internal Failures 3. This code is common in diesel vehicles equipped with selective catalytic reduction (SCR) systems, which use DEF to reduce Repair Information for P249D code. If you've seen this on your Duramax you know the frustration of ge. The only way I can get rid of it is turning the SCR system off. One such code is P249D, which indicates an issue with the closed-loop reductant injection control system. Troubles going bact to stock with a P249D I'm having troubles with a P249D code after returning everything back to stock after changing emission tables, I'm not sure if it's related but this code is there right after clearing it even before a engine start. The dreaded Reductant Fluid Quality Poor indicator is on and there is a P249D code stored. at first I taught it was a bad battery, but it has been replaced, have tried jumping with a fully charged battery, and a running car as well. The code still comes up every single key cycle. Decoding the P249D Code on Duramax Engines: Comprehensive Guide to Causes, Symptoms, and Expert Solutions. qfr bdjou evsiiw rqmroye kmmihut qqn oaj siosmv ejwb ikihk