EGR Deactivated ( Plugged? ) NOX exceeds allowable spec.
NOX are Oxides of Nitrogen and nasty smog causing junk.
Common for this year to plug the EGR cooler or have an EGR failure.
This is also one of the codes you run into if you don't do your emissions delete correctly.
It says NOx Exceedence - Deactivation of EGR.
Low oil pressure
Trouble code P0234 means:Engine overboost condition
Trouble code P0177 means:Fuel composition sensor circuit range/performance
Camshaft position sensor circuit malfunction.
Trouble code P0483 means: Fan Performance
Trouble code P1693 means: A companion DTC was set in both the ECM and PCM
Trouble code P0573 means:Cruise control/brake switch A circuit high
my book says code 0123 THROTTLE/PEDAL POSITION SENSOR/SWITCH A CIRCUIT HIGH INPUT
The U3FFF code on a Dodge 2500 diesel typically refers to an issue related to the exhaust gas recirculation (EGR) system or the diesel particulate filter (DPF). This code may indicate that the vehicle's computer has detected a fault in the emissions control system, which can affect engine performance and emissions compliance. It's advisable to use a diagnostic scanner to confirm the exact issue and consult a mechanic for proper diagnosis and repair.
Trouble code P0680 means: Reserve for future glow plugs 9-12
#2 warm air heater relay wiring fault