TSB210183-082420

9/3/2021
Fault Code 5655: SCR System Test Failing NOx Sensors on Low Hour Aftertreatment Systems
Technical Service Bulletin
Technical Service Bulletin: TSB210183
Released Date: 24-Aug-2021
Fault Code 5655: SCR System Test Failing NOx Sensors on Low Hour Aftertreatment
Systems
Fault Code 5655: SCR System Test Failing NOx
Sensors on Low Hour Aftertreatment Systems
Warranty Statement
The information in this document has no effect on present warranty coverage or repair practices,
nor does it authorize TRP or Campaign actions.
Contents
Product Affected
L9 CM2450 L126B
Issue Summary
Symptom:
The SCR System test fails the NOx sensor rationality portion of the test, directing the
technician to replace the NOx sensors.
Root Cause:
If the unit has over 200 engine hours and has not had the aftertreatment replaced, proceed
with published troubleshooting direction.
Software tuning can cause the SCR System Test to falsely fail NOx sensors when the
aftertreatment diesel oxidation catalyst (DOC) and/or aftertreatment selective catalytic
reduction catalyst (SCR) have less than 200 engine hours.
Verification
Verify the aftertreatment SCR catalyst or aftertreatment DOC have less than 200 engine hours.
Resolution
If the unit has less than 200 engine hours or the aftertreatment has been replaced in the last 200
engine hours, perform the following steps:
Do not replace the NOx sensors.
Complete the remaining published troubleshooting steps.
Clear the fault codes.
https://quickserve.cummins.com/qs3/pubsys2/xml/en/tsb/2021/tsb210183.html
1/2
9/3/2021
Fault Code 5655: SCR System Test Failing NOx Sensors on Low Hour Aftertreatment Systems
Operate engine following conditions to clear the fault code.
If fault codes do not return, release the unit to the customer.
If fault codes return, follow the local escalation process.
Document History
Date
2021-8-20
Details
Module Created
Last Modified: 24-Aug-2021
https://quickserve.cummins.com/qs3/pubsys2/xml/en/tsb/2021/tsb210183.html
2/2