Violation code

393.17B2LRLDWR

Lighting - Tail lamp - Both Lamps on rearmost vehicle driveaway missing when required to be on.

Not in SMSOOS· FMCSA A&I All Violations

393.17B2LRLDWR is a Vehicle violation under 49 CFR §393.17B2LRLDWR. It is an out-of-service violation; it is not scored in the SMS. Nationally it was cited 112 times in the last five years, with an OOS rate of 95.5%.

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National roadside inspection stats

as of 9/20/2026

Inspections

111

that found this code

Violations

112

total written

OOS rate

95.5%

107 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.

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Not used in SMS BASIC scoring

Recorded on your inspection report and visible on the PSP, but contributes 0 points to CSA BASIC scores — even if cited Out-of-Service.

Violation group: Vehicle
Regulation §: 393.17B2LRLDWR
Severity weight: N/A
Used in SMS: No
Status: Active
Updated: 9/20/2026

Last updated September 2026

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What 393.17B2LRLDWR means — and how to avoid it

In plain English

In plain terms, 393.17B2LRLDWR is cited for lighting - Tail lamp - Both Lamps on rearmost vehicle driveaway missing when required to be on. It falls under the FMCSA rules on parts and accessories needed for safe operation. Because it’s an out-of-service condition, an inspector can put the driver or vehicle out of service on the spot until it’s corrected.

What the inspector checks

•Required lamps present, clean, and working — headlamps, tail, stop, turn, marker
•Reflective sheeting/reflectors intact
•Trailer cord and connections making contact

How to prevent it

✓Walk the lights on every pre-trip (have someone confirm brake/turn)
✓Carry spare bulbs/fuses and swap a dead lamp before rolling
✓Clean lenses and check the trailer plug for corrosion

How it affects your CSA

0 CSA points

393.17B2LRLDWR is not scored in the SMS. It adds 0 CSA points — even if written out-of-service — but it still appears on the inspection report and the driver’s PSP.

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 393.17B2LRLDWR through FMCSA DataQs

If this violation was written incorrectly, here are the angles trucking-safety managers use to contest it. Playbook: Codes not used in SMS scoring.

Common ways to challenge this code

Not used in SMS — should not affect BASIC
This code is on the inspection report but is excluded from SMS BASIC scoring per Appendix A. Use DataQs to correct the underlying data quality issue if the code was written in error, but understand it does not affect the CSA percentile.
Evidence that wins
- ✓FMCSA SMS Methodology Appendix A reference
- ✓Underlying inspection report

Common pitfalls — avoid these

⚠These codes still appear on PSP — challenge the data if the cite was wrong

⚡ Draft a challenge for 393.17B2LRLDWR →Read the DataQs guide first

Other Vehicle codes

Codes under the same FMCSA violation group

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Frequently asked questions about 393.17B2LRLDWR

What does violation 393.17B2LRLDWR mean?

393.17B2LRLDWR is the FMCSA roadside-inspection violation code for "Lighting - Tail lamp - Both Lamps on rearmost vehicle driveaway missing when required to be on.", part of the Vehicle group, cited under 49 CFR §393.17B2LRLDWR.

What BASIC does 393.17B2LRLDWR affect?

393.17B2LRLDWR is not scored in any CSA BASIC. It is recorded on the inspection report and appears on the PSP, but it contributes 0 points to a carrier's SMS BASIC percentiles.

Is 393.17B2LRLDWR an out-of-service (OOS) violation?

Yes. 393.17B2LRLDWR is an out-of-service violation, meaning the driver or vehicle can be placed out of service at the roadside until the issue is corrected. OOS violations also add an extra severity point in SMS scoring.

How many CSA points does 393.17B2LRLDWR add?

393.17B2LRLDWR adds 0 CSA points because it is not used in SMS scoring, even when written out of service.

How can a driver prevent 393.17B2LRLDWR?

Walk the lights on every pre-trip (have someone confirm brake/turn); Carry spare bulbs/fuses and swap a dead lamp before rolling; Clean lenses and check the trailer plug for corrosion.

Can 393.17B2LRLDWR be challenged through DataQs?

Yes. If you believe 393.17B2LRLDWR 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 393.17B2LRLDWR Carrier CSA lookup CSA glossary

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