2020–2022 Mack MD: service brakes, hydraulic recall
An unsecured brake pedal can cause a loss of braking ability and increase the risk of a crash.
What was reported
Source: manufacturer filing, 49 CFR Part 573Reported to NHTSA Sep 1, 2021 by Mack Trucks, Inc, owners notified Sep 13, 2021.
Which vehicles are covered
Source: NHTSA campaign 21V684000| Model year | On WhichTrim |
|---|---|
| 2020 Mack MD | — |
| 2021 Mack MD | — |
| 2022 Mack MD | — |
None of the vehicles this campaign names has a page on WhichTrim: the catalogue covers the cars, trucks and SUVs the EPA certifies from 2016 on, and these vehicles fall outside it — older model years, or motorhomes, trailers, buses, motorcycles and chassis cabs the EPA does not rate. The campaign record above is complete as filed, and whether one specific vehicle is included is settled by its VIN. Other campaigns on vehicles without a page here →
How much of it has been fixed
Source: manufacturer quarterly report, 49 CFR 573.7of the campaign
The final figure: the six quarters of reporting that 49 cfr 573.7 requires have closed.
This is the manufacturer's own cumulative count of vehicles it has inspected and repaired, divided by the vehicles the campaign covers. It files that count with NHTSA every quarter for six consecutive quarters, starting from the quarter in which owners were told a remedy was ready, and then the obligation ends — so a figure on an older campaign is where the count stopped, not where it stands today.
It rarely reaches 100%, and not because the work was not done. The same report asks manufacturers to count vehicles they could not reach at all — exported, stolen, scrapped, or simply never located — and those stay in the denominator. A low number means a lot of these vehicles are still out there unrepaired; it does not tell you which ones.
The federal paperwork
Source: nhtsa.govFiled documents
- Owner letter PDF — The letter mailed to registered owners, in full.
- Remedy instructions PDF — What the dealer is told to actually do about it.
Check one specific vehicle
A recall applies to a build range, so year, make and model cannot settle it. NHTSA checks a VIN against the manufacturer's own list and tells you whether the repair is still outstanding on that vehicle.
NHTSA VIN recall lookup →Campaign 21V684000 · the manufacturer calls it SC0429
Own one, or run a fleet? Recall Watch checks each VIN against every new NHTSA campaign and emails you when one lands, this one's expansions included. Or take a free one-line alert by model year.
Common questions
Source: NHTSA, 49 CFR Part 573What does this advisory mean?
Do not drive means exactly that: the manufacturer is telling owners to stop driving the vehicle until the repair is done. These are the two most serious things NHTSA can attach to a campaign, and both mean the risk exists while the vehicle is switched off.
Is SC0429 the same recall as 21V684000?
Yes. SC0429 is the number Mack Trucks, Inc uses for this campaign in its own paperwork and in the letter it sends owners. 21V684000 is the number NHTSA files it under. One recall, two references — dealers and service departments generally quote the manufacturer's.
Does this recall repair cost anything?
No. Federal law requires the manufacturer to remedy a safety defect or a compliance failure at no charge, for vehicles up to 15 years old measured from the date of first sale. A dealer that asks you to pay for a recall repair is in the wrong.
How do I know whether my vehicle is included?
By VIN, not by model year. The manufacturer files a build range with NHTSA and only vehicles inside it are covered, so two identical-looking cars from the same year can differ. NHTSA's own lookup checks a VIN against the manufacturer's list.
What if the repair is not available yet?
It happens, and often. Manufacturers must notify owners when a defect is found even if the parts or the software are not ready, then notify them a second time once the remedy exists. The remedy filed for this campaign is described above.
What did the manufacturer say was wrong?
The problem, risk and fix quoted on this page are the manufacturer's own words as filed with NHTSA under 49 CFR Part 573. WhichTrim does not paraphrase them.
Who started this recall?
NHTSA's record credits the manufacturer. A recall can begin with the manufacturer's own testing, with a defect investigation, or with a compliance test against a Federal Motor Vehicle Safety Standard.