FRAME AS 1474356 - Caterpillar

Introduction
The purpose of this document is to enhance the ability to troubleshoot the diagnostic trouble codes listed for all CT13 engines with SCR.Diagnostic Trouble Codes
Table 1
DTC     Description    
3216-4     NOx IN signal out of range low    
3216-10     NOx IN signal abnormal rate of change    
3216-13     NOx IN out of calibration    
3216-20     NOx IN signal drifted high    
3216-21     NOx IN signal drifted low    
3226-4     NOx OUT signal out of range low    
3226-10     NOx OUT signal abnormal rate of change    
3226-13     NOx OUT out of calibration    
3226-21     NOx OUT signal drifted low    Diagnostic Steps
Table 2
Step     Action     Decision    
1     Verify that your fault code is on the list above. Is your fault code the only active fault code?     Yes: Go to Step 2    
No: Diagnose other active faults and retest
2     Is the NOx Sensor Module connector, harness, and terminals clean and undamaged?     Yes: Replace appropriate NOx sensor.    
No: Repair harness, connector, or terminal damage. When repair is complete, retest for codes.