Recall 21V659 covers 1,934 2016-2021 Thomas Built Buses Saf-T-Liner Hdx school buses for power-steering-hose fire risk. Repair will be free once available.
Thomas Built Buses is recalling 1,934 2016-2021 Saf-T-Liner Hdx school buses with ISL or L9 engines because the power steering hose is routed too close to power cables. A worn hose increases the risk of a fire, and the dealer repair will be free once Thomas Built Buses finishes the remedy.
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What's wrong?
The power steering hose on 2016-2021 Thomas Built Buses Saf-T-Liner Hdx school buses carries pressurized steering fluid for the hydraulic assist system. That assist system reduces the effort needed to turn the front wheels, especially at low speed or when maneuvering a loaded bus.
On affected buses with an ISL or L9 engine, the hose is routed too close to power cables. That lack of clearance lets the hose and cable rub against each other during normal vibration and movement. Over time, the contact wears the hose or cable surface and raises the risk of a heat-related thermal event.
There is no warning sign before failure. Because the problem is the routing of the hose near the power cables, an owner or driver is not expected to notice a change before the damaged area creates a thermal event risk.
Who's affected?
Covers six model years of the same bus model, all tied to the power steering system.
| 2016 Thomas Built Buses Saf-T-Liner Hdx | power steering system |
|---|---|
| 2017 Thomas Built Buses Saf-T-Liner Hdx | power steering system |
| 2020 Thomas Built Buses Saf-T-Liner Hdx | power steering system |
| 2021 Thomas Built Buses Saf-T-Liner Hdx | power steering system |
| 2019 Thomas Built Buses Saf-T-Liner Hdx | power steering system |
| 2018 Thomas Built Buses Saf-T-Liner Hdx | power steering system |
| Units affected | 1,934 |
| Field incidents | NHTSA has logged 2 field incidents to date. |
A matching year and model does not guarantee inclusion. Check your VIN to confirm whether this recall applies to your specific bus.
What's the safety risk?
A worn power steering hose increases fire risk on included 2016-2021 Thomas Built Buses Saf-T-Liner Hdx buses under NHTSA campaign 21V659. If your VIN is included, plan service promptly and ask the dealer for current repair timing. Repair will be free at any franchised Thomas Built Buses dealer once available.
What should I do?
- Check your VIN to confirm your 2016-2021 Thomas Built Buses Saf-T-Liner Hdx is included in this recall.
- Watch for Thomas Built Buses repair instructions before scheduling service, since the remedy is still listed as under development.
- Call Thomas Built Buses customer service at 1-800-547-0712 with questions and reference recall number 21V659 when you call.
- Keep the bus away from service until Thomas Built Buses confirms the power-steering-hose routing has been inspected or modified for clearance from the power cables.
- Report any power steering fluid leak, hose damage, smoke, or burning smell to the service desk before the bus is moved.
What happens at the repair
Once the remedy is available, a Thomas Built Buses technician will inspect the power steering hose routing and modify it so the hose has proper clearance from the power cables. The final dealer repair will be free once it opens, and parts and labor are covered under the recall. Until then, contact an authorized Thomas Built Buses service facility for interim handling if the bus needs service before the recall repair opens.
Timeline
| August 25, 2021 | NHTSA published the recall |
|---|---|
| October 15, 2021 | Owner notification mailed |
| October 17, 2021 | Dealer notification began |
| October 17, 2021 | Dealer notification ended |
| October 17, 2021 | Interim owner notification (was planned for this date) |
Frequently asked questions
What is recall 21V659?
Recall 21V659 covers 1,934 2016-2021 Thomas Built Buses Saf-T-Liner Hdx school buses with an ISL or L9 engine. The power steering hose can have inadequate clearance near power cables. A worn hose increases fire risk, and DTNA will inspect and modify the routing for free.
What should I do if my 2016-2021 Thomas Built Buses Saf-T-Liner Hdx is on this recall?
Check your VIN to confirm your specific bus is included in recall 21V659. If it is, contact a franchised Thomas Built Buses dealer or DTNA customer service at 1-800-547-0712 for inspection and repair instructions. Reference recall FL898 when you call.
Is the recall repair free?
Yes. Federal recall law requires the manufacturer to repair the defect at no cost. DTNA will inspect the power steering hose routing and modify it as necessary free of charge through the recall process.
What is the safety risk?
The safety risk is fire. The recall says the power steering hose can be routed too close to power cables. If the hose wears, that damage increases the risk of a fire. Confirm the VIN, then arrange the free inspection and routing modification.
What if I bought this bus used?
The free recall repair still applies. Recall coverage follows the VIN, not the first owner. Check your VIN to confirm whether this specific Saf-T-Liner Hdx is included, then give recall 21V659 or DTNA recall FL898 to the dealer service desk.
More information
| NHTSA campaign page | nhtsa.gov/vehicle-recalls/21V659000 |
|---|---|
| Thomas Built Buses customer service | 1-800-547-0712 |
| NHTSA recall # | 21V659 |
| NHTSA recall # (full) | 21V659000 |
Source documents
-
Download Recall Document (PDF) (PDF) - Download Quarterly Report (PDF)
- Download Owner Notice (PDF)
- Download Misc. Document (PDF)
- Download Owner Notification Letter (PDF)
- Download Recall Report (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 →