2020–2022 Mack MD Service Brakes Recall 21V684000 (Mack SC0429)
NHTSA recall 21V684000 (Mack recall SC0429) covers about 2,823 2020–2022 Mack MD vehicles (service brakes), filed with NHTSA Sep 1, 2021. NHTSA lists a DO-NOT-DRIVE advisory: owners should not drive these vehicles until the repair is done.
Source: NHTSA campaign 21V684000 · Data as of Nov 6, 2026 · By CarWhere Research
Do not drive: NHTSA safety advisory
NHTSA lists a do-not-drive advisory for this campaign. Owners should not drive affected vehicles until the recall repair is done.
What's recalled
Component: Service brakes
Mack Trucks, Inc. (Mack) is recalling certain 2020-2022 Mack MD vehicles. The cotter pin that retains the brake pedal clevis pin may not have been properly installed, which could result in an unsecured brake pedal.
The risk
An unsecured brake pedal can cause a loss of braking ability and increase the risk of a crash.
The remedy and its status
Owners are advised to not drive their vehicles until the remedy has been performed. Dealers will inspect the cotter pin installation and repair it as necessary, free of charge. Owner notification letters were mailed on September 13, 2021. Owners may contact Mack's customer service at 1-800-866-1177. Mack's number for this recall is SC0429.
Status: NHTSA lists Sep 13, 2021 as the owner-notification date for this campaign.
Mack recall number SC0429
NHTSA lists the manufacturer's own recall number for 21V684000 as SC0429. Owner letters and dealer service departments often use this code, so a search for "SC0429 recall" refers to the same campaign.
Affected models and years
Models and model years NHTSA lists for this campaign. Not every vehicle of a listed model and year is included; check by VIN.
| Vehicle | Model years | More |
|---|---|---|
| Mack MD | 2020–2022 | — |
Key dates
- Report filed with NHTSA
- Sep 1, 2021
- Owner notification
- Sep 13, 2021
- Recall initiated by
- the manufacturer
- Filed by
- Mack Trucks, Inc.
Check your VIN for 21V684000
- Find the 17-character VIN on the driver-side dashboard (visible through the windshield), the door-jamb sticker, or your registration.
- Enter it in NHTSA's free VIN recall lookup. It shows every open recall on that exact vehicle, including this one if it applies and hasn't been repaired.
- If 21V684000 is open, call any Mack dealer's service department and give them the recall number (21V684000 or SC0429). The repair is free.
Not sure of the exact model or year? Decode it first with the free VIN decoder.
Frequently asked questions
What is recall 21V684000?
NHTSA recall 21V684000 (Mack recall SC0429) covers about 2,823 2020–2022 Mack MD vehicles (service brakes), filed with NHTSA Sep 1, 2021. NHTSA lists a DO-NOT-DRIVE advisory: owners should not drive these vehicles until the repair is done. It covers certain 2020-2022 Mack MD vehicles.
Is it safe to drive a vehicle with recall 21V684000?
No. NHTSA's record for 21V684000 carries a do-not-drive advisory: owners should not drive the vehicle until the recall repair is done. Contact a Mack dealer to arrange the repair.
How do I know if my vehicle is affected by 21V684000?
Only a VIN lookup can tell you. Not every vehicle of the listed models and years is included, and repaired vehicles drop off. Enter your 17-character VIN in NHTSA's free recall lookup at nhtsa.gov/recalls, or ask any Mack dealer to check it.
What is the fix for recall 21V684000, and is it free?
NHTSA's record says: "Owners are advised to not drive their vehicles until the remedy has been performed." NHTSA lists Sep 13, 2021 as the owner-notification date for this campaign. Safety-recall repairs are done free of charge at authorized dealers.
What is the Mack recall number for 21V684000?
NHTSA lists the manufacturer's own recall number as SC0429. Dealers and owner letters often use that code (SC0429) instead of the NHTSA campaign number 21V684000.
Sources and method
- NHTSA recall record for 21V684000, from NHTSA's public recall campaign database. Problem, risk and remedy text is NHTSA's own wording.
- "Vehicles affected" is NHTSA's potential-units-affected count for the whole campaign.
- Data as of Nov 6, 2026. NHTSA updates campaigns as manufacturers file amendments, so check the official record for the latest.
Related recalls
- 25V666000: 2019–2025 Mack (5 models) seat belts (Oct 6, 2025)
- 23V746000: 2024 Mack MD steering (Nov 7, 2023)