AI Damage2021 Mack LR: common problems
The maker issued 163 service bulletins for this year. Details by component below, with sources.
Key figures
- Technical service bulletins (TSB)
- 163
Components owners complain about
| Component | Owner complaints | involving a crash | Technical service bulletins (TSB) |
|---|---|---|---|
| Engine and cooling | 0 | 0 | 74 |
| Electrical system | 0 | 0 | 37 |
| Powertrain | 0 | 0 | 23 |
| Engine | 0 | 0 | 12 |
| Equipment | 0 | 0 | 11 |
| Fuel system | 0 | 0 | 9 |
| Service brakes | 0 | 0 | 7 |
| Suspension | 0 | 0 | 7 |
| Fuel/propulsion system | 0 | 0 | 4 |
| Structure | 0 | 0 | 3 |
| Vehicle speed control | 0 | 0 | 3 |
| Wheels | 0 | 0 | 3 |
| Communication | 0 | 0 | 1 |
| Electronic stability control | 0 | 0 | 1 |
Comparison
What to check before buying
- Engine and cooling. Radiator and fan after a frontal hit, coolant level and condition, overheating.
- Electrical system. Scan all modules, test the battery and alternator, inspect connectors near the impact zone.
- Powertrain. Shift quality under load, harsh shifts, transmission codes, CV joints.
- Engine. Cold start, unusual noises, oil leaks and engine codes.
Manufacturer service bulletins
Bulletin titles as filed with NHTSA.
- CBR - Mack Chassis - Through Shaft Bearing Retainer Breakage On Mack Carriers
- CBR - Mack Carrier Nut Adhesive Change
- CBR - No Start Condition After Over the Air Programing
- CBR - Mack DEF Level (UQLS) Sensor Troubleshooting Guide - US17+OBD16 Emissions to US22+OBD2023 (DOES NOT…
CBR - Mack DEF Level (UQLS) Sensor Troubleshooting Guide - US17+OBD16 Emissions to US22+OBD2023 (DOES NOT APPLY TO AN(4) and PR(4)).
- CBR - Mack Temperature Sensor Troubleshooting Guide
- CBR - Hard Steering Due to Steering Column Miter Box Corrosion – Inspection and Replacement Procedure
- CBR - When an OTA (Over-The-Air) job starts to program the VECU blocks the starter relay out, if the job…
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 - To correct the MID136 SID 66 FMI 7 fault code the latest Bendix VCP file will need to downloaded
- CBR - A significant GPS reporting issue is affecting fleet operations, with trucks maintaining back-office…
CBR - A significant GPS reporting issue is affecting fleet operations, with trucks maintaining back-office communication but failing to transmit GPS location data.
- Mack DEF Level (UQLS) Sensor Troubleshooting Guide - US17+OBD16 Emissions and Newer
- Remote Control Central Door Lock, Programming; Key Fob Cannot Be Programmed Or Does Not Work After…
Remote Control Central Door Lock, Programming; Key Fob Cannot Be Programmed Or Does Not Work After Programming - Model Year 2018 And Newer
- Vehicles Equipped With a Common Rail Fuel System - Aftermarket Secondary Fuel Filters, Important…
Vehicles Equipped With a Common Rail Fuel System - Aftermarket Secondary Fuel Filters, Important Information On Approved Filters - US17+OBD16 toUS21+OBD23
NHTSA lists 163 bulletins for this year; the 12 newest are shown here.
Other years of this model
Questions and answers
What are the most common problems with the 2021 Mack LR?
There are no owner complaints in the NHTSA data for this year; the data comes from 163 manufacturer service bulletins.
How many service bulletins (TSB) were issued for the 2021 Mack LR?
NHTSA lists 163 manufacturer service bulletins for this year. A bulletin tells dealers how to diagnose or fix a known issue; it is not a recall.
Should I buy a 2021 Mack LR from a US auction?
Owner complaints describe defects, not crash damage. Before bidding, check the components listed above and review the lot photos: VinWind builds a report of visible and hidden damage by VIN.
Other 2021 models
Read also
Sources: public NHTSA data (USA): service bulletins and owner complaints; YouTube: links to videos credited to their authors. Complaints are owner statements not verified by NHTSA, and describe defects rather than crash damage. Data updated 2026-11-04.