TSB210183

3/29/22, 12:51 PM
Fault Code 5655: SCR System Test Failing NOx Sensors on Low Hour Aftertreatment Systems
Technical Service Bulletin
Technical Service Bulletin: TSB210183
Released Date: 21-Mar-2022
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.
Compare the ECM code and revision number in the ECM to the calibration revisions listed in
the ECM Calibration Revision History Database on QuickServe® Online (QSOL) for
applicable changes related to this SCR System Test.
Resolution
If the unit has less than 200 engine hours or the aftertreatment has been replaced in the last
200 engine hours, verify the ECM calibration revision is February 2022 or later.
If an ECM calibration code update for this fault code is available, the ECM calibration revision
must be that revision or higher. Refer to Procedure 019-032 in Section 19.
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Fault Code 5655: SCR System Test Failing NOx Sensors on Low Hour Aftertreatment Systems
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Perform the test again. Refer to Procedure 014-025 in Section 14.
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Follow the direction given by the test.
Complete the remaining published troubleshooting steps.
If fault codes return, follow the local escalation process.
Document History
Date
Details
2021-8-20
Module Created
2022-3-21
Updated Verification section. Updated Resolution section.
Last Modified: 21-Mar-2022
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