Violation code

396.3A1BOS

Brake - Defective brake(s) are equal to or greater than 20% of the service brakes on the vehicle/combination.

Vehicle Maintenance0Non-OOS· SMS Appendix A v3.20

396.3A1BOS is a Brake Out Of Service violation under 49 CFR §396.3A1BOS. It falls in the Vehicle Maintenance BASIC with a severity weight of 0/10. Nationally it was cited 272,981 times in the last five years, with an OOS rate of 99.7%.

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National roadside inspection stats

as of 9/20/2026

Inspections

271,829

that found this code

Violations

272,981

total written

OOS rate

99.7%

272,209 OOS

Source: FMCSA roadside inspection data (last 5 years). The OOS rate is the share of these violations that led the officer to mark the driver or vehicle out of service.

Violation group: Brake Out Of Service
Regulation §: 396.3A1BOS
Severity weight: —
Used in SMS: Yes
Status: Active
Updated: 9/20/2026

Last updated September 2026

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Notes

DSMS: N | Comment: Added in 3.0.7 | Footnote: This violation took effect in the SMS with the April 28, 2017 run; when 396.3A1BOS is cited and recorded as an OOS violation, it receives a weight of 2.

What 396.3A1BOS means — and how to avoid it

In plain English

In plain terms, 396.3A1BOS is cited for brake - Defective brake(s) are equal to or greater than 20% of the service brakes on the vehicle/combination. It falls under the FMCSA rules on inspection, repair, and maintenance.

What the inspector checks

•Brake adjustment and pushrod stroke within limits
•Air loss/leaks, low-air warning, and reservoir pressure
•Cracked, worn, or contaminated linings, drums, and rotors
•Hoses/tubing chafing, kinked, or leaking

How to prevent it

✓Check brake adjustment and listen for air leaks at every pre-trip
✓Fix air leaks and warning-light faults before dispatch — don’t “drive it in”
✓Put brakes on the PM schedule and document the work

How it affects your CSA

0 CSA points

Severity 0/10. A fresh citation counts at the 3× time weight — up to 0 points toward the Vehicle Maintenance BASIC — then tapers to 2× after 6 months and 1× after a year, dropping off the score at 24 months.

General guidance from the violation’s FMCSA classification — not legal advice, and not a substitute for the inspector’s findings or 49 CFR.

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Challenging 396.3A1BOS through FMCSA DataQs

If this violation was written incorrectly, here are the angles trucking-safety managers use to contest it. Playbook: Vehicle Maintenance (general).

Relevant 49 CFR49 CFR § 396.3

Inspection, repair, and maintenance

“Every motor carrier and intermodal equipment provider must systematically inspect, repair, and maintain, or cause to be systematically inspected, repaired, and maintained, all motor vehicles and intermodal equipment subject to its control.”

Common ways to challenge this code

Pre-trip inspection showed compliant brakes
The driver's pre-trip DVIR documented compliant brake adjustment and operation. The cited defect arose en route or was misclassified at roadside.
Evidence that wins
- ✓Driver Vehicle Inspection Report (DVIR) from that date
- ✓Repair invoice or shop record
- ✓Post-citation re-inspection certificate (clean)
Momentary failure exception (§393.9)
The required lamp was inoperative only momentarily due to vibration, temperature, or similar transient cause — explicitly exempted under §393.9.
Evidence that wins
- ✓Photograph showing the lamp operable before / after the stop
- ✓Repair invoice if a fuse or bulb was replaced
Tread measurement disputed
The tread depth measurement was taken at a worn point that is not representative, contrary to NHTSA/FMCSA measurement standards.
Evidence that wins
- ✓Independent tread gauge reading from same tire (multiple positions)
- ✓Photograph of the tire with a reference scale
Documented maintenance schedule disproves the defect
Carrier's periodic-inspection records show the cited defect could not reasonably have existed at the time of inspection.
Evidence that wins
- ✓Periodic inspection certificate (§396.17)
- ✓Maintenance work order proximate to inspection date

Common pitfalls — avoid these

⚠DataQs cannot remove a violation simply because the defect was repaired after the stop

⚡ Draft a challenge for 396.3A1BOS →Read the DataQs guide first

More codes in Vehicle Maintenance

Same BASIC category — ranked by national citation volume

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Frequently asked questions about 396.3A1BOS

What does violation 396.3A1BOS mean?

396.3A1BOS is the FMCSA roadside-inspection violation code for "Brake - Defective brake(s) are equal to or greater than 20% of the service brakes on the vehicle/combination.", part of the Brake Out Of Service group, cited under 49 CFR §396.3A1BOS.

What BASIC does 396.3A1BOS affect?

396.3A1BOS falls under the Vehicle Maintenance BASIC in the FMCSA Safety Measurement System (SMS).

What is the CSA severity weight of 396.3A1BOS?

396.3A1BOS carries a severity weight of 0 out of 10. Higher weights indicate violations more closely tied to crash risk, and they count more toward a carrier's Vehicle Maintenance score.

Is 396.3A1BOS an out-of-service (OOS) violation?

No. 396.3A1BOS is not an out-of-service violation, so on its own it does not trigger an out-of-service order at the roadside.

How many CSA points does 396.3A1BOS add to a carrier's score?

The point contribution of 396.3A1BOS depends on its severity weight (0/10) multiplied by a time weight of 3, 2, or 1 based on how recent the inspection is. You can calculate the exact contribution with the CSA points calculator.

How can a driver prevent 396.3A1BOS?

Check brake adjustment and listen for air leaks at every pre-trip; Fix air leaks and warning-light faults before dispatch — don’t “drive it in”; Put brakes on the PM schedule and document the work.

Can 396.3A1BOS be challenged through DataQs?

Yes. If you believe 396.3A1BOS was recorded in error, you can file a Request for Data Review (RDR) through the FMCSA DataQs system with supporting evidence. A successful challenge can remove or correct the violation on your record.

Keep going

CSA points calculator How to challenge a violation Draft a DataQs letter for 396.3A1BOS Vehicle Maintenance BASIC Carrier CSA lookup CSA glossary

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