Recall 18V409 covers 109 2017-2018 Thomas Built Buses Saf-T-Liner Efx school buses for misplumbed air-brake check valves. Free repair at a franchised dealer.
Thomas Built Buses is recalling 109 2017-2018 Saf-T-Liner Efx school buses because an air brake check valve can be plumbed incorrectly, letting both air systems lose pressure during rapid secondary air pressure loss. That pressure loss can make the parking brakes activate suddenly and increase crash risk; Thomas Built Buses dealers will complete the repair free of charge.
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What's wrong?
The air brake check valve on 2017-2018 Thomas Built Buses Saf-T-Liner Efx school buses is a one-way valve in the brake air supply. Its job is to keep air moving in the intended direction and help separate the primary air system from the secondary air system. That separation matters because each side of the air brake system needs its own protected air supply.
On affected buses, the air lines were attached to the wrong ports on the check valve. When the valve is plumbed that way, the primary air system is not isolated from the secondary air system as designed. The problem traces to installation work during the build period, not to a changed part design.
There is no warning sign before failure. A brake inspection found the issue on a new bus, so the practical clue is inspection results, not a dashboard symptom or driver feel.
Who's affected?
Covers the 2017 and 2018 model years, with the same brake system check valve issue in both.
| 2017 Thomas Built Buses Saf-T-Liner Efx | brake system |
|---|---|
| 2018 Thomas Built Buses Saf-T-Liner Efx | brake system |
| Units affected | 109 |
| Field incidents | NHTSA has logged no field incidents to date. |
A matching year and model does not guarantee inclusion. Check your VIN to confirm whether your specific bus is included.
What's the safety risk?
An incorrectly plumbed check valve can cause rapid air loss in both brake air systems after secondary-system pressure drops. The parking brakes can activate suddenly, which increases crash risk. Treat any air-pressure problem as a reason to pull over safely and call the dealer. Repair is free at any franchised Thomas Built Buses dealer.
What should I do?
- Check your VIN to confirm your 2017-2018 Thomas Built Buses Saf-T-Liner Efx is included in this recall.
- Contact your nearest franchised Thomas Built Buses dealer to schedule the free air-brake check-valve inspection and repair that isolates the primary and secondary air systems.
- Bring the recall notice if Thomas Built Buses has mailed one. If not, reference recall number 18V409 and DTNA recall FL-774 when you call.
- Use extra caution until the repair is complete, especially if the air system loses pressure or the parking brakes apply unexpectedly.
What happens at the repair
At the dealer, a Thomas Built Buses technician inspects the air brake system check valve and repairs the plumbing if it is routed incorrectly. The work is available now through the recall, and parts and labor are covered. The goal is to restore proper separation between the primary and secondary air systems so the brake air circuits isolate as designed. Ask the service desk to confirm campaign 18V409 on the repair order.
Timeline
| June 15, 2018 | NHTSA published the recall |
|---|---|
| August 12, 2018 | Owner notification mailed |
| August 13, 2018 | Dealer notification began |
| August 13, 2018 | Dealer notification ended |
| August 13, 2018 | Interim owner notification (was planned for this date) |
Frequently asked questions
What is recall 18V409?
Recall 18V409 covers 109 2017-2018 Thomas Built Buses Saf-T-Liner Efx school buses with an incorrectly plumbed air-brake check valve. A rapid air-pressure loss can affect both brake air systems and cause the parking brakes to activate suddenly, increasing crash risk.
What should I do if my 2017-2018 Thomas Built Buses Saf-T-Liner Efx is on this recall?
Check your VIN to confirm your specific bus is included in recall 18V409. If it is, contact a franchised Thomas Built Buses dealer to schedule inspection and repair of the air-brake check valve. Reference recall number 18V409 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. A franchised Thomas Built Buses dealer will inspect the air-brake check valve and repair it for free.
What is the safety risk?
The safety risk is sudden parking-brake activation after a rapid air-pressure loss. If the check valve is plumbed incorrectly, air loss in the secondary system can also drain the primary system. That can cause the parking brakes to apply suddenly and increase crash risk.
When did Thomas Built Buses start this recall repair?
Thomas Built Buses began the recall repair on August 12, 2018. Owners can contact Thomas Built Buses customer service at 1-800-547-0712 or call a franchised dealer with recall number 18V409 to schedule the free inspection and repair.
More information
| NHTSA campaign page | nhtsa.gov/vehicle-recalls/18V409000 |
|---|---|
| Thomas Built Buses customer service | 1-800-547-0712 |
| NHTSA recall # | 18V409 |
| NHTSA recall # (full) | 18V409000 |
Source documents
-
Download Misc. Document (PDF) - Download Recall Investigation Document (PDF) (PDF)
- Download Owner Notification Letter (PDF)
- Download Recall Report (PDF)
- Download Quarterly Report (PDF)
- Download Recall Acknowledgement (PDF)
This article is generated from NHTSA's primary recall filings and reviewed against the source on May 25, 2026. RecallNotify does not paraphrase NHTSA's consequence language; that text is reproduced as written above. Editorial standards →