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Service bulletins for the 2021 Mack MD

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.

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

By type

By component

By trouble code

Only bulletins with component: Engine are shown. Show all

Bulletins, newest first
CBR 2107-22 2026012026-02-02. Service bulletin. ENGINE. CBR - Mack DEF Level (UQLS) Sensor Troubleshooting Guide - US17+OBD16 Emissions to US22+OBD2023 (DOES NOT APPLY TO AN(4) and PR(4)).
CBR 2107-21 2025052025-06-02. Service bulletin. FUEL/PROPULSION SYSTEM; ENGINE. Mack DEF Level (UQLS) Sensor Troubleshooting Guide - US17+OBD16 Emissions and Newer
CBR-561 2025032025-04-02. Service bulletin. ENGINE. If oil dilution is suspected refer to the applicable CBR solution below: ∙ CBR-659􀁡Mack Chassis - Oil Diluted With Fuel; Fuel In Oil, Diagnostic Information - All Emissions, All Model Years
CBR-997 2024112024-12-02. Service bulletin. ENGINE. Vehicles may present with oil leak coming from the clutch/flywheel housing and observation of burned clutch smell or clutch slipping. These symptoms can be mistaken as a crankshaft rear main seal leak, when the actual cause is the crankshaft adaptor O-ring.
CBR-2013 2024042024-05-01. Service bulletin. ENGINE AND ENGINE COOLING. CBR: Turbo Compound (TC) Hot Side Noise, Diagnostic Information.
M-258-014 2023092023-10-03. Service bulletin. ENGINE AND ENGINE COOLING:ENGINE:DIESEL; ENGINE AND ENGINE COOLING. TSB: Aftertreatment Diesel Exhaust Fluid (DEF) Tank, Level Sensor, Replacement
M-258-012 2023092023-10-03. Service bulletin. ENGINE AND ENGINE COOLING; FUEL SYSTEM, DIESEL:DELIVERY:PRESSURE SENSOR; ENGINE AND ENGINE COOLING:ENGINE:DIESEL. TSB: Aftertreatment Diesel Exhaust Fluid (DEF) Tank, Level Sensor, Replacement
CBR-2112 2023072023-08-02. Service bulletin. ELECTRICAL SYSTEM; POWER TRAIN; ENGINE AND ENGINE COOLING. CBR: Programming Failure - Chassis With Cummins Engine And An Allison Transmission
M-265-0022022-10-06. Service bulletin. ENGINE AND ENGINE COOLING. TSB-Charge Air Cooler t-clamp install.
CBR-21312022-09-08. Service bulletin. ENGINE AND ENGINE COOLING. USE FOR NEW VEHICLES (US21+OBD22 Emissions) - Intermittent Diagnostic Trouble Codes U02A3, U029D, U029E
KC-21392022-09-07. Service bulletin. ENGINE AND ENGINE COOLING; FUEL SYSTEM, DIESEL. fuel in the oil inspection
KC-7332022-07-05. Service bulletin. ENGINE AND ENGINE COOLING. Back Office Mack Chassis - Secondary Gauge Set Up - Model Year 2018 and Newer.
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-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-5612022-07-05. Service bulletin. ENGINE AND ENGINE COOLING. 11L, 13L, And 16L Engine Oil Analysis Specifications - US10 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-7502022-07-05. Service bulletin. ENGINE AND ENGINE COOLING. US10 Emission Engines - Diagnostic Trouble Code ( DTC ) SPN 1231 FMI 9 Troubleshooting.
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-21712022-06-07. Service bulletin. ENGINE AND ENGINE COOLING. Temperature Sensor Troubleshooting Guide - US10+OBD13 And Newer
KC-21652022-06-07. Service bulletin. ENGINE AND ENGINE COOLING. DEF Pump 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.