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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
CBR-2383 2024062024-07-03. Service bulletin. UNKNOWN OR OTHER; ELECTRICAL SYSTEM; VEHICLE SPEED CONTROL. CBR - Accelerator Pedal: Inspection Instructions
CBR-2139 2024052024-06-04. Service bulletin. FUEL/PROPULSION SYSTEM; ENGINE. CBR: Vehicles built with an 11 liter engine may experience a complaint of excessive fuel in the oil. It is possible that the source of the fuel is the rear fuel galley plug in the cylinder head. A new and improved fuel galley plug has been developed to resolve this issue.
CBR-2013 2024042024-05-01. Service bulletin. ENGINE AND ENGINE COOLING. CBR: Turbo Compound (TC) Hot Side Noise, Diagnostic Information.
CBR-1008 2024042024-05-01. Service bulletin. POWER TRAIN. CBR: Equipped With An Automated Manual Transmission Model D or F ( AMT-D, AMT-F, mDrive) Missing X1 Value In VDA And Default Settings Guidelines, ParameterP1AOB; Fault Code P1052-54, Error 40,Or Error 18 Encountered During Clutch Or Tran.
CBR-2139 2024032024-04-02. Service bulletin. ENGINE AND ENGINE COOLING. CBR: Vehicles built with an 11 liter engine may experience a complaint of excessive fuel in the oil. It is possible that the source of the fuel is the rear fuel galley plug in the cylinder head.
CBR-2350 2024022024-03-05. Service bulletin. ELECTRICAL SYSTEM. CBR -Telematics Gateway (TGW) Connect Ability Issues
CBR-2347 2024022024-03-05. Service bulletin. ELECTRICAL SYSTEM. CBR - Active "Set Park Brake" Message On Drivers Information Display (DID).
CBR-202 2024022024-03-05. Service bulletin. POWER TRAIN. CBR - Automated Manual Transmission ( AMT ) Flywheel Pilot Bearing Wear On Input Shaft.
CBR-2014 2024022024-03-05. Service bulletin. SUSPENSION. CBR - Driveline Noise, Suspension Ride Height Too High, Suspension Will Not Exhaust - Chassis Built 2016w01 And Newer.
CBR-2333 2024012024-02-02. Service bulletin. ELECTRICAL SYSTEM. CBR: TGW Will Not Connect After SIM Card Replacement
CBR-2320 2023122024-01-03. Service bulletin. ENGINE AND ENGINE COOLING. CBR: For vehicles equipped with an 11L engine, the plastic saddle bracket holding the a/c line on the left side of the engine may move excessively and rub the area where it secures the line.
M-465-001 2023112023-12-05. Service bulletin. POWER TRAIN. TSB: Mack Trucks now offer an improved HD Inter-Axle Through Shaft for the CRD 125, 150, 180, and 200 family carriers. The new HD shaft went into production on January 23rd, 2023 for 2.54 - 3.50 axle ratios and April 1st, 2023 for 3.56 - 3.98 ratios. The new HD through shaft is an upgrade over the current standard shaft and can now be used as a replacement part instead of the standard shaft. The new HD shaft has a new design to increase strength, longevity and life over the standard shaft.
CBR-399 2023102023-11-03. Service bulletin. ELECTRICAL SYSTEM; ELECTRICAL SYSTEM: INSTRUMENT CLUSTER/PANEL. CBR: 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
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
M728-005A 2023082023-09-06. Service bulletin. SUSPENSION. TSB: Barksdale Leveling Valve, Leak Test
CBR-2131 2023082023-09-06. Service bulletin. ENGINE AND ENGINE COOLING; ELECTRICAL SYSTEM. CBR: Intermittent Diagnostic Trouble Codes U02A3,U029D, U029E - USE FOR NEW VEHICLES (US21+OBD22 Emissions)
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
CBR-2303 2023072023-08-02. Service bulletin. ENGINE AND ENGINE COOLING:EXHAUST SYSTEM; ENGINE AND ENGINE COOLING. CBR: Mack DEF Dosing Valve Diagnostic Trouble Codes (DTC) P202D00, P208E00, P103B00 - US10+OBD13 And Newer Emissions
KC-22892023-07-06. Service bulletin. ENGINE AND ENGINE COOLING. Diagnostic Trouble Code (DTC) P103200: Particulate Matter Sensor Removed from Exhaust - US21+OBD22 Emissions
KC-2094 Rev 32023-07-06. Service bulletin. EQUIPMENT:ELECTRICAL:INFOTAINMENT; ELECTRICAL SYSTEM. Infotainment System - Volume Drop During A Phone Call, Phone Connected Via Bluetooth
KC-22922023-07-06. Service bulletin. SUSPENSION. Vehicles Equipped With Chalmers Suspension - Frame Bracket Hardware Loose or Interfering
KC-2043 Rev 42023-07-06. Service bulletin. ENGINE AND ENGINE COOLING:ENGINE:ENGINE CONTROL MODULE (ECU/ECM); ELECTRICAL SYSTEM. Engine Control Module (EMS) Software (MSW) Information - Improvement List, Through June 2023 - US21+OBD2020 Emissions
KC-2116 Rev 92023-07-06. Service bulletin. ENGINE AND ENGINE COOLING. Mack NOx Sensor Troubleshooting Guide - US10+OBD13 And Newer Emissions
KC-2116 Rev 82023-07-06. Service bulletin. ENGINE AND ENGINE COOLING. Mack NOx Sensor Troubleshooting Guide - US10+OBD13 And Newer Emissions
KC-2158 Rev 62023-07-06. Service bulletin. ENGINE AND ENGINE COOLING; ELECTRICAL SYSTEM; ENGINE AND ENGINE COOLING:EXHAUST SYSTEM:EMISSION CONTROL. CBR - Mack 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.