AI Damage2021 Peterbilt 520: common problems
The maker issued 56 service bulletins for this year. Details by component below, with sources.
Key figures
- Technical service bulletins (TSB)
- 56
Components owners complain about
| Component | Owner complaints | involving a crash | Technical service bulletins (TSB) |
|---|---|---|---|
| Electrical system | 0 | 0 | 16 |
| Engine | 0 | 0 | 14 |
| Engine and cooling | 0 | 0 | 9 |
| Fuel system | 0 | 0 | 6 |
| Equipment | 0 | 0 | 5 |
| Fuel/propulsion system | 0 | 0 | 3 |
| Powertrain | 0 | 0 | 3 |
| Service brakes | 0 | 0 | 3 |
| Forward collision avoidance | 0 | 0 | 2 |
| Steering | 0 | 0 | 2 |
| Visibility | 0 | 0 | 2 |
| Electronic stability control | 0 | 0 | 1 |
| Structure | 0 | 0 | 1 |
| Suspension | 0 | 0 | 1 |
Comparison
What to check before buying
- Electrical system. Scan all modules, test the battery and alternator, inspect connectors near the impact zone.
- Engine. Cold start, unusual noises, oil leaks and engine codes.
- Engine and cooling. Radiator and fan after a frontal hit, coolant level and condition, overheating.
- Fuel system. Fuel smell, leaks, rough running, fuel-system codes.
Manufacturer service bulletins
Bulletin titles as filed with NHTSA.
- "Kenworth
Dealers should check the chassis list and SIR weekly for VIN changes. 2 chassis added to the chassis list. Peterbilt: Dealers should check the chassis list and SIR weekly for VIN changes. 10 chassis added to the…
- The verbiage in the Introduction section has been updated
- The procedure has been updated to include additional steps for verifying the software level on the vehicle…
The procedure has been updated to include additional steps for verifying the software level on the vehicle electronic control unit (VECU2) and digital display (DD). Steps have also been added to the PACCAR Common Rail…
- This optional software update is now available for chassis equipped with EMY 2021B-2023 PACCAR MX-11 and…
This optional software update is now available for chassis equipped with EMY 2021B-2023 PACCAR MX-11 and MX-13 engines. This update provides customers with additional time to service their trucks before a DEF-related…
- The Condition, Chassis Affected, Service Action, Warranty, and Procedure sections have been updated to…
The Condition, Chassis Affected, Service Action, Warranty, and Procedure sections have been updated to include the latest prognostics bulletin verbiage. The Warranty section has also been updated to include Peterbilt…
- "The software is not yet available
The bulletin will be updated when more information is available."
- Additional US chassis have been added, along with additional Canadian chassis under identical safety…
- "An optional software update will be available on 07/06/2026 for chassis equipped with EMY…
"An optional software update will be available on 07/06/2026 for chassis equipped with EMY 2021B-2023PACCAR MX-11 and MX-13 engines. This update provides customers with additional time to service theirtrucks before a…
- "KW & PB 14 fuel injector part numbers (seven for MX-11 and seven for MX-13 engines) have been added to…
"KW & PB 14 fuel injector part numbers (seven for MX-11 and seven for MX-13 engines) have been added to this warranty policy."
- "KW
A new recommended repair has been added to verify the software level and close the campaign in SIR.The repair procedure has been updated with additional note boxes for clear instructions. PB: The repair procedure has…
- Updated the point of contact for sourcing the MX Engine Overlay Harness Kits
This retrofit should have been completed by 5/15/2022 per the Action section of the bulletin. However, trucks still open in SIR are still eligible for the repairs.
- Certain Peterbilt Model 520 BEV chassis with an Accelera Power Control and Accessory System (PCAS) were…
Certain Peterbilt Model 520 BEV chassis with an Accelera Power Control and Accessory System (PCAS) were manufactured without a check valve in the power steering system.
NHTSA lists 56 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 Peterbilt 520?
There are no owner complaints in the NHTSA data for this year; the data comes from 56 manufacturer service bulletins.
How many service bulletins (TSB) were issued for the 2021 Peterbilt 520?
NHTSA lists 56 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 Peterbilt 520 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.