Recall 26V139 affects 775 2022-2027 Mack Terrapro (Te) trucks because ECU software allows engine starts in gear. Repair is free at any franchised Mack dealer.
Mack is recalling 775 2022-2027 Terrapro (Te) trucks because ECU software can let the engine start when the transmission is not in Neutral. Starting in gear can cause unexpected vehicle movement and raise the risk of a crash or injury, and Mack dealers will complete the repair free of charge.
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What's wrong?
The affected 2022-2027 Mack Terrapro (Te) trucks use engine control unit software to manage when the starter is allowed to engage. That software includes a vehicle ECU parameter, which is a setting that tells the truck whether the transmission must be in Neutral before the engine starts.
On these trucks, that parameter was set to the wrong value. With the wrong setting, the starter interlock does not enforce the Neutral-only start condition the way it should, so the engine can start while the proprietary transmission is in another position.
There is no warning sign before failure. The recall information does not describe a dashboard light, message, sound, or other driver notice before the truck starts when the transmission is not in Neutral.
Who's affected?
Spans six model years of Terrapro (Te) trucks, all using the same vehicle ECU software parameter.
| 2027 Mack Terrapro (Te) | Software |
|---|---|
| 2026 Mack Terrapro (Te) | Software |
| 2025 Mack Terrapro (Te) | Software |
| 2024 Mack Terrapro (Te) | Software |
| 2023 Mack Terrapro (Te) | Software |
| 2022 Mack Terrapro (Te) | Software |
| Units affected | 775 |
| Field incidents | NHTSA has logged no field incidents to date. |
The year and model narrow the scope, but the VIN decides. Check your VIN to confirm whether your specific truck is included.
What's the safety risk?
Starting the Terrapro while it is in gear can make the vehicle move unexpectedly, increasing the risk of a crash or injury. There is no warning sign before this happens, so confirm the transmission is out of gear before starting and schedule the ECU update soon. Repair is free at any franchised Mack dealer.
What should I do?
- Check your VIN to confirm your 2022-2027 Mack Terrapro (Te) is included in this recall.
- Contact a franchised Mack dealer to schedule the free ECU software update that fixes the engine-start interlock issue.
- Bring the recall notice if Mack mailed one. If not, reference recall number 26V139 or Mack recall SC0492 when you call.
- Verify the transmission is in Neutral before starting the truck until the software update is complete.
- Call Mack customer service at 1-800-866-1177 with questions about the recall.
What happens at the repair
At the dealer, a Mack technician updates the engine control unit software so the starter interlock logic matches the required neutral start behavior. The software update is free under the recall, and parts and labor are covered. Mack used its standard reimbursement plan for this recall. If you already paid out of pocket for a related ECU software repair before the recall notice, contact Mack customer service and keep repair documentation for the claim.
| Reimbursement | Reimbursement available |
|---|
Timeline
| March 11, 2026 | NHTSA published the recall |
|---|---|
| March 18, 2026 | Dealer notification began |
| March 18, 2026 | Dealer notification ended |
| March 18, 2026 | VIN-searchable in NHTSA's database — Check your VIN to see whether this recall applies to your specific vehicle. |
| April 14, 2026 | Owner notification mailed |
| May 8, 2026 | Interim owner notification (was planned for this date) |
Frequently asked questions
What is recall 26V139?
Recall 26V139 covers 775 2022-2027 Mack Terrapro (Te) trucks with ECU software that can let the engine start when the transmission is not in Neutral. Mack dealers will update the ECU software for free.
What should I do if my 2022-2027 Mack Terrapro (Te) is on this recall?
Check your VIN to confirm your specific truck is included in recall 26V139. If it is, contact a franchised Mack dealer to schedule the ECU software update. Reference Mack recall number SC0492 when you call. The repair is free.
Is the recall repair free?
Yes. Federal recall law requires the manufacturer to repair the defect at no cost, and Mack will update the ECU software free of charge at any franchised Mack dealer.
What is the safety risk in recall 26V139?
The safety risk is unexpected vehicle movement during engine start. If the truck starts while the transmission is in gear, it can move unexpectedly and increase the risk of a crash or injury. The dealer repair is a free ECU software update.
When were owners notified about this Mack recall?
Mack mailed owner notification letters on April 14, 2026. VINs became searchable on March 18, 2026. If you own a 2022-2027 Mack Terrapro (Te), check your VIN and call a franchised Mack dealer or Mack customer service at 1-800-866-1177.
More information
| NHTSA campaign page | nhtsa.gov/vehicle-recalls/26V139000 |
|---|---|
| Mack customer service | 1-800-866-1177 |
| NHTSA recall # | 26V139 |
| NHTSA recall # (full) | 26V139000 |
Source documents
-
Download Owner Notification Letter (PDF) - Download Owner Notice (PDF)
- Download Recall Acknowledgement (PDF)
- Download Recall Report (PDF)
This article is generated from NHTSA's primary recall filings and reviewed against the source on May 19, 2026. RecallNotify does not paraphrase NHTSA's consequence language; that text is reproduced as written above. Editorial standards →