Recall 21V953 affects 20,668 2008-2022 Mack vehicles because a brake valve leak can release the parking brake. Repair is free at any franchised Mack dealer.
Mack is recalling 20,668 2008-2022 Terrapro (Mru), Mru, Te, and Terrapro (Te) trucks under recall 21V953 because a brake control valve air leak can create excessive back pressure and release the parking brake unexpectedly. A released parking brake can let the truck roll away and increase crash risk; Mack dealers will complete the repair free of charge.
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What's wrong?
On the 2008-2022 Mack trucks in this recall, the PP1 parking brake control valve is mounted in the dash. That valve is the control the driver uses to apply and release the parking brake. Air from the valve vents through an exhaust fitting and tube, so the brake system can change state cleanly when the driver moves the control.
The problem starts when the valve leaks air internally. The attached exhaust tube cannot vent that air volume fast enough, so back pressure builds in the line. That pressure can overcome the parking brake control and release the parking brake unexpectedly, even though the driver applied it.
Owners or operators can notice air leaking from the valve or air coming out of the exhaust pipe when the parking brake is applied. Those sounds or visible air movement are the warning signs before the parking brake releases unexpectedly.
Who's affected?
This recall spans Mack's MRU and TE TerraPro name variants, all tied to the same PP1 parking brake valve and exhaust tube.
| 2018 Mack Terrapro (Mru) | Parking brake |
|---|---|
| 2013 Mack Terrapro (Mru) | Parking brake |
| 2012 Mack Terrapro (Mru) | Parking brake |
| 2021 Mack Te | Parking brake |
| 2009 Mack Mru | Parking brake |
| 2019 Mack Te | Parking brake |
| 2014 Mack Terrapro (Mru) | Parking brake |
| 2017 Mack Terrapro (Mru) | Parking brake |
| 2011 Mack Terrapro (Mru) | Parking brake |
| 2019 Mack Terrapro (Mru) | Parking brake |
| 2008 Mack Mru | Parking brake |
| 2015 Mack Terrapro (Mru) | Parking brake |
| 2022 Mack Terrapro (Te) | Parking brake |
| 2020 Mack Te | Parking brake |
| 2016 Mack Terrapro (Mru) | Parking brake |
| 2010 Mack Mru | Parking brake |
| Units affected | 20,668 |
| Field incidents | NHTSA has logged 10 field incidents to date. |
A matching year and model does not guarantee inclusion. Check your VIN to confirm whether your specific truck is included in this recall.
What's the safety risk?
A parking brake that releases unexpectedly can let the vehicle roll away and increase the risk of a crash. Air leaking from the valve or exhaust pipe when the park brake is applied is the warning sign to take seriously. Secure the vehicle and schedule the recall repair soon. Repair is free at any franchised Mack dealer.
What should I do?
- Check your VIN to confirm your 2008-2022 Mack Terrapro (Mru), Te, Mru, or Terrapro (Te) is included in this recall.
- Contact a franchised Mack dealer to schedule the free exhaust-tube and fitting removal that stops valve back pressure from releasing the parking brake.
- Reference recall number 21V953 when you call the dealer.
- Bring the recall notice if Mack mailed one to you.
- Avoid leaving the truck where a rollaway would put people or traffic at risk until the repair is complete.
What happens at the repair
At the dealer, a Mack technician removes the exhaust tube and fitting from the brake control valve involved in the recall. Parts and labor are covered under the recall, so the repair is free. Mack used its general reimbursement plan on file for this campaign. If you already paid out of pocket for the same repair before the recall notice, contact Mack customer service about documented reimbursement under that plan.
| Reimbursement | Reimbursement available |
|---|
Timeline
| December 9, 2021 | NHTSA published the recall |
|---|---|
| December 17, 2021 | Dealer notification began |
| December 17, 2021 | Dealer notification ended |
| February 4, 2022 | VIN-searchable in NHTSA's database — Check your VIN to see whether this recall applies to your specific vehicle. |
| February 4, 2022 | Interim owner notification (was planned for this date) |
| February 8, 2022 | Owner notification mailed |
Frequently asked questions
What is recall 21V953?
Recall 21V953 covers 20,668 2008-2022 Mack Terrapro (Mru), Te, Mru, and Terrapro (Te) vehicles with a brake control valve air leak that can release the parking brake unexpectedly. Mack dealers remove the exhaust tube and fitting from the valve for free.
What should I do if my 2008-2022 Mack Terrapro (Mru), Te, Mru, or Terrapro (Te) is on this recall?
Check your VIN to confirm your specific vehicle is included in recall 21V953. If it is, contact a franchised Mack dealer to schedule the parking brake valve repair. Reference recall number 21V953 and Mack recall number SC0433 when you call.
Is the recall repair free?
Yes. Federal recall law requires the manufacturer to repair the defect at no cost. Mack dealers will remove the exhaust tube and fitting from the brake control valve free of charge, including parts and labor.
What is the safety risk in recall 21V953?
The safety risk is an unexpected parking brake release. In recall 21V953, air leaking into the exhaust hose can create excessive back pressure and allow the vehicle to roll away, increasing crash risk. Keep the vehicle secured until the dealer completes the free repair.
What if I bought my Mack vehicle used?
The free recall repair still applies. Federal recall law follows the vehicle, not the original buyer. Check your VIN to confirm whether your specific Mack vehicle is included, then call a franchised Mack dealer or Mack customer service at 1-800-866-1177.
More information
| NHTSA campaign page | nhtsa.gov/vehicle-recalls/21V953000 |
|---|---|
| Mack customer service | 1-800-866-1177 |
| NHTSA recall # | 21V953 |
| NHTSA recall # (full) | 21V953000 |
Source documents
-
Download Recall Document (PDF) (PDF) - Download Quarterly Report (PDF)
- Download Recall Report (PDF)
- Download Recall Investigation Document (PDF) (PDF)
- Download Owner Notification Letter (PDF)
- Download Owner Notice (PDF)
- Download Recall Acknowledgement (PDF)
This article is generated from NHTSA's primary recall filings and reviewed against the source on May 20, 2026. RecallNotify does not paraphrase NHTSA's consequence language; that text is reproduced as written above. Editorial standards →