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Service bulletins for the 2021 Mack LR

A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.

163 on file from NHTSA, as of 2026-10-19.

By type

By component

By trouble code

Bulletins, newest first
KC-21072022-07-05. Service bulletin. ENGINE AND ENGINE COOLING. DEF Level (UQLS) Sensor Troubleshooting Guide - US17+OBD16 Emissions and Newer.
KC-21122022-07-05. Service bulletin. ELECTRICAL SYSTEM; POWER TRAIN; ENGINE AND ENGINE COOLING. Programming Failure - Chassis With Cummins Engine And An Allison Transmission
KC-21162022-07-05. Service bulletin. ENGINE AND ENGINE COOLING. NOx Sensor Troubleshooting Guide - US10+OBD13 And Newer Emissions.
KC-21432022-07-05. Service bulletin. VEHICLE SPEED CONTROL. (Back Office) - Cruise Control Inoperative After Updating Software VECU5 Without ESP Package (UESP).
KC-21572022-07-05. Service bulletin. ENGINE AND ENGINE COOLING; FUEL SYSTEM, GASOLINE. Aftertreatment Hydrocarbon Injector (AHI) Troubleshooting Guide - US10+OBD13 And Newer Emissions.
KC-21582022-07-05. Service bulletin. ENGINE AND ENGINE COOLING. Selective Catalytic Reduction (SCR) Muffler Troubleshooting Guide - US10+OBD13 And Newer Emissions.
KC-21652022-07-05. Service bulletin. ENGINE AND ENGINE COOLING. DEF Pump Troubleshooting Guide - US10+OBD13 And Newer Emissions.
KC-3992022-07-05. Service bulletin. ELECTRICAL SYSTEM. Vehicle Overspeed Warning Comes Active At A Lower Speed Than Expected; Vehicle Overspeed Warning In Driver Information Display (DID) - Model Year 2018 And Newer With New Style Instrument Cluster.
KC-4052022-07-05. Service bulletin. POWER TRAIN. Warranty Automated Manual Transmission ( AMT, I-Shift, mDrive ) Control Housing Assembly; Guidelines For Filing A Claim For Chassis Return Visit With Transmission Issues After A Repair Requiring Control Housing Removal And Reinstallation - US07 And N.
KC-5612022-07-05. Service bulletin. ENGINE AND ENGINE COOLING. 11L, 13L, And 16L Engine Oil Analysis Specifications - US10 And Newer Emissions
KC-7352022-07-05. Service bulletin. EQUIPMENT. Premium Tech Tool (PTT) - Message For Data Mismatch, Product Configuration Mismatch; Instruction To Run An Accessory Kit Displayed When Attempting To Run Diagnostics For Diagnostic Trouble Codes (DTC) Or Programming - US10+OBD13 And Newer Emissions,
KC-7362022-07-05. Service bulletin. ENGINE AND ENGINE COOLING. (Back Office Only) - Engine Brake Vibration When In High Setting - 13L Engine With Variable Geometry Turbo ( VGT ) - US17 And Newer Emissions (Common Rail Fuel System).
KC-7452022-07-05. Service bulletin. POWER TRAIN. Automated Manual Transmission ( AMT ) I-Shift / mDRIVE - Ribbon Harness Replacement - Speed Sensor Bolts, Possible Fault Codes P1058 - 21 Or MID 130 PID 161 FMI 1
KC-7502022-07-05. Service bulletin. ENGINE AND ENGINE COOLING. US10 Emission Engines - Diagnostic Trouble Code ( DTC ) SPN 1231 FMI 9 Troubleshooting.
KC-7512022-07-05. Service bulletin. POWER TRAIN. Vehicles Equipped With An Automated Manual Transmission Model D or F ( AMT-D, AMT-F ) - Transmission Oil Leakage From Transmission Input Shaft Seal Or Output Shaft Seal - US10 And Newer Emissions, Common Model Years 2010 And Newer.
KC-6632022-06-07. Service bulletin. ENGINE AND ENGINE COOLING. Emcon (Spark Assist) Engine Aftertreatment System Troubleshooting Check Sheet - US07 Emissions
KC-6442022-06-07. Service bulletin. ENGINE AND ENGINE COOLING. Manual Compression Test Adapter For Engines With Stainless Steel Injector Sleeves (Conical Tip Injectors) - US07 And Newer Emissions, Model Year 2008 And Newer
KC-6272022-06-07. Service bulletin. EQUIPMENT. Premium Tech Tool ( PTT ) Training Materials And Support Tools
KC-21722022-06-07. Service bulletin. UNKNOWN OR OTHER; ELECTRICAL SYSTEM. No Start Condition After Over The Air Programing - VECU5 No Start "Safe State"
KC-21712022-06-07. Service bulletin. ENGINE AND ENGINE COOLING. Temperature Sensor Troubleshooting Guide - US10+OBD13 And Newer
KC-21702022-06-07. Service bulletin. SUSPENSION. Electronically Controlled Suspension (ECS) Losing Air Pressure
KC-21692022-06-07. Service bulletin. ELECTRICAL SYSTEM. Low Voltage Disconnect (LVD), Function Description
KC-21652022-06-07. Service bulletin. ENGINE AND ENGINE COOLING. DEF Pump Troubleshooting Guide - US10+OBD13 And Newer Emissions
KC-21612022-06-07. Service bulletin. ENGINE AND ENGINE COOLING. DEF Pump Cycling periodically Hours After Key Off
KC-21582022-06-07. Service bulletin. ENGINE AND ENGINE COOLING. Selective Catalytic Reduction (SCR) Muffler Troubleshooting Guide - US10+OBD13 And Newer Emissions

The summaries are NHTSA's. Each bulletin's page links NHTSA's copy of the manufacturer's document.