NUT 3F0701 - Caterpillar

Diesel Exhaust Fluid (DEF) Concentration and Low Conversion Codes
Issue
There have been cases where both the tank refill method and continuous refill method have had a diagnostic code go active, then disappear, and the become active again over a short period.Resolution
The sensitivity and severity of the DEF concentration has been updated to address false diagnostic codes for DEF concentration and low conversion.De-Crystal Regeneration Priority over Common Rail System (CRS) Nozzle Heat Cycle
Issue
Currently the CRS nozzle heat cycles are preventing the high carbon evaporation-based Selected Catalyst Reduction (SCR) injector de-crystallization regeneration from running.The DEF injector failures occurring at early hours on Tier 4 Final in-line engine products are leading to fault codes and inducements which can cause customer downtime.Resolution
The de-crystallization regeneration will prevent a CRS nozzle heater cycle as long as there is no Nozzle Heater Event level 2.Implementation of DEF System Flow Evaluation
Issue
There was a high rate of partially blocked DEF injectors replaced under warranty.Resolution
Changed the DEF flow evaluation based on the DEF injector command and proportional change in DEF pump speed.Data Health Diagnostic Strategy Robustness
Issue
Diagnostic codes for data link communication have caused inducement to trigger and engine shutdowns.Complete loss of communication between the engine ECM and after-treatment ECM resulting in code 2348-9 SAE J1939 Data Link #2 : Abnormal Update Rate.Complete loss of communication between the after-treatment ECM and engine exhaust out NOx sensors, or between the Aftertreatment ECM and the Dosing Control Unit (DCU) resulting in code 5856-9 SAE J1939 Data Link #3 : Abnormal Update Rate.Resolution
Changed the response time for SAE J1939 Data Link #2 to allow for recovery of the datalink.Changed the response time for SAE J1939 Data Link #3 to allow for recovery of the datalink.NOx Sensor Diagnostic Robustness
Issue
-12 and -11 diagnostic codes cause false diagnosis and replacement of NOx sensors. Returned sensors are found to have no fault.Resolution
For -12 codes the dwell time was increased between the first report and second report. If a second event triggers the -12 code will become active.Removed the -11 code and rolled the qualification for NOx sensor -11 code logic into the NOx sensor -12 code logic. Troubleshooting is same for the -11 and -12 code.Strategy Improvements to Existing DEF Quality
Issue
3516-2 Aftertreatment #1 DEF Concentration : Erratic, Intermittent, or Incorrect : The DEF quality sensor is unable to read the DEF concentration due to an optical path obstruction. The DEF concentration is high or low.Resolution
Estimated DEF level lowered to less than 20% to reduce false codes.The conditions for low/high DEF concentration and pass condition changes:Allow codes to reset during keyswitch ON and engine off conditions.Allow codes to reset when below the ambient temperature threshold conditions.EGR Mass Flow Events Improvements
Issue
Variances in engine speed and fuel can cause variances in EGR flow rate. These changes can trigger a low flow code. This low flow rate occurs at 1500 rpm and 1950 rpm engine speed.Resolution
Added filtered desired value to isolate the high frequencies.Operator Inducement Emergency Override Reset
Issue
The "Operator Inducement Emergency Override Timer Reset" currently allows resetting even though the override