6/1/2021

Intake Air Heater Stuck Relay and Intake Air Heater Damage: Fault Code 383

Technical Service Bulletin
Technical Service Bulletin: TSB210032
Released Date: 20-May-2021
Intake Air Heater Stuck Relay and Intake Air Heater Damage: Fault Code 383

Intake Air Heater Stuck Relay and Intake Air Heater Damage: Fault
Code 383
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.
Information Only - OEM Related Matter Not Covered By Cummins® - Contact Appropriate OEM Dealer or OEM Representative For
Additional Information

Contents
Product Affected
ISB6.7 CM2350 B101
B6.7 CM2350 B121B
B6.7 CM2450 B155B
Issue
Symptom:
Fault code 383 is active
Intake air heater malfunctions and engine has trouble starting
Root Cause:
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Intake Air Heater Stuck Relay and Intake Air Heater Damage: Fault Code 383

Intake air heater relay stuck closed leading to extended on-time of the heater. Units experiencing Fault Code 383 may have
experienced extended on-time of the intake air heater with no air flow entering the system caused by a stuck relay, causing the
air heater to overheat. The isolated power connection bar may expand and lift from the top surface of the intake manifold cover
due to extended on-time (Figure 1). The isolated power connection bar may also become loose. The issue may progress and
exhibit electrical arcing damage to the intake air heater internal joints (Figure 2), with potential for arcing to cause debris to drop
into the intake system.
Verification
Inspect the insulated power connection bar for deformation. See Figure 1 below. Removal of the intake manifold cover is not
necessary to inspect the insulated power connection bar.
Check if the intake air heater power terminal can be moved by hand. See Figure 3 below.

Figure 1, Example View of Power Bar Deformation from Top Surface of Intake Manifold Cover.
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Intake Air Heater Stuck Relay and Intake Air Heater Damage: Fault Code 383

Figure 2, Example of Arcing Damage on Internal Joints of Intake Air Heater.

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Intake Air Heater Stuck Relay and Intake Air Heater Damage: Fault Code 383

Figure 3, Any Movement of The Terminal Back and Forth As Shown is Unacceptable.
Resolution
Intake air heater damage that exhibits power connection bar deformation or movement of the terminal back and forth is due to
intake air heater relay failure and is not covered under Cummins ® warranty. Repair locations are to contact the OEM for further
repair direction.
For Navistar® and IC Bus applications reference iKnow article IK1201457.

Document History
Date
2021-2-11

Details
Module Created

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Intake Air Heater Stuck Relay and Intake Air Heater Damage: Fault Code 383

Date

Details

2021-2-17

Corrected Product Affected.

2021-4-5

Updated Verification and Resolution sections. Updated Figure 2.

2021-5-20

Added reference to iKnow article IK1201457.

Last Modified: 20-May-2021

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