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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

Only bulletins with component: Electrical system are shown. Show all

Bulletins, newest first
CBR 2712-7 0320262026-04-02. Service bulletin. ELECTRICAL SYSTEM; UNKNOWN OR OTHER. CBR - No Start Condition After Over the Air Programing.
CBR 2171-11 2025112025-12-03. Service bulletin. ENGINE; ELECTRICAL SYSTEM. CBR - Mack Temperature Sensor Troubleshooting Guide
CBR 2172-5 0820252025-09-02. Service bulletin. ELECTRICAL SYSTEM. CBR - When an OTA (Over-The-Air) job starts to program the VECU blocks the starter relay out, if the job ends in a Critical failure, the vehicle will remain in Safe State.
CBR 407 0720252025-08-04. Service bulletin. SERVICE BRAKES; ELECTRICAL SYSTEM. CBR - To correct the MID136 SID 66 FMI 7 fault code the latest Bendix VCP file will need to downloaded.
CBR 2488 0720252025-08-04. Service bulletin. ELECTRICAL SYSTEM. CBR - A significant GPS reporting issue is affecting fleet operations, with trucks maintaining back-office communication but failing to transmit GPS location data.
CBR 901-5 2025052025-06-02. Service bulletin. ELECTRICAL SYSTEM. Remote Control Central Door Lock, Programming; Key Fob Cannot Be Programmed Or Does Not Work After Programming - Model Year 2018 And Newer
CBR-570 2024092024-10-03. Service bulletin. ELECTRICAL SYSTEM; FUEL/PROPULSION SYSTEM. CBR: US17 GHG Common Rail Fuel System Component Electrical Faults - Model Year 2017 To 2024
CBR-471 2024092024-10-03. Service bulletin. ELECTRICAL SYSTEM. CBR: The procedure to eliminate the Mack Chassis "Air Restriction Light On" seen in the cluster is to confirm that the parameter YYT is set to "Enable" with Premium Tech Tool.
CBR-2391 2024082024-09-04. Service bulletin. ELECTRICAL SYSTEM; POWER TRAIN. CBR: Diagnostic Trouble Code (DTC) U010187- Lost Communication With TECU
CBR-2350 2024072024-08-01. Service bulletin. ELECTRICAL SYSTEM. CBR: Telematics Gateway (TGW) Connect Ability Issues
CBR-2383 2024062024-07-03. Service bulletin. UNKNOWN OR OTHER; ELECTRICAL SYSTEM; VEHICLE SPEED CONTROL. CBR - Accelerator Pedal: Inspection Instructions
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-2333 2024012024-02-02. Service bulletin. ELECTRICAL SYSTEM. CBR: TGW Will Not Connect After SIM Card Replacement
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
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
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-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-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
KC-22642023-05-03. Service bulletin. ELECTRICAL SYSTEM. CBR: Mack Chassis - Allison Reduced Engine Load At A Stop (RELS) Diagnostic Trouble Code P071a Or P07ce - GR,TE,LR Models - Non-Split/Drop Box PTO
KC-21282023-04-04. Service bulletin. ENGINE AND ENGINE COOLING:EXHAUST SYSTEM:EMISSION CONTROL; ELECTRICAL SYSTEM. Engine Control Module (EMS) Software Information - Improvement List (Change Log), March 2023 – US21+OBD2021 Emissions ONLY
KC-22012023-01-07. Service bulletin. ELECTRICAL SYSTEM. Engine Control Module (EMS) Software (MSW) Information – October 2022; Improvement List (Change Log) - US21+OBD22 (13L VGT, TC) And US17+OBD22 (11L) Emissions
KC-21402022-12-05. Service bulletin. ELECTRICAL SYSTEM; PARKING BRAKE. Mack Chassis - P05E662 Park brake Sensor/Switch Circuit Range/Performance, Signal Compare failure - Diagnostic Instructions - US21+OBD21 Emissions
KC-3282022-12-05. Service bulletin. ELECTRICAL SYSTEM. Diagnostic Trouble Codes (DTC) P208064, P208464, P242B64 and P246F64 Lighting The Malfunction Indicator Lamp (MIL) - US17+OBD19 And Newer Emissions, Model Years 2020 and Newer

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