What 392.71B-MC means in plain language
FSMCR 392.71B-MC is a carrier-level violation. It applies when a motor carrier—not the driver, but the company itself—permits or requires a driver to operate a commercial motor vehicle equipped with a radar detector, or instructs a driver to use one while driving.
This is different from a driver personally choosing to use a radar detector on their own. The violation focuses on the carrier's action or inaction: either explicitly requiring radar detector use, or knowingly allowing it to happen without stopping it. If your carrier told you to use a radar detector, or if your carrier knew you were using one and didn't prohibit it, the citation lands on the carrier's record, not yours—though you may still be cited under the related driver code 392.71A-D in the same inspection.
Radar detectors are banned in CMVs under federal safety rules. The carrier is responsible for enforcing that ban internally through policy and driver communication.
What our enforcement data actually shows
Across our 13 million+ inspection records, 392.71B-MC is cited very rarely. All-time, we see 61 citations for this code. In the last 12 months, enforcement volume was 38 citations, and in the last 90 days, 10 citations were issued.
The out-of-service rate for 392.71B-MC is 0.0%—none of the 61 citations resulted in a vehicle being placed out of service. This is significantly lower than the all-FMCSR average out-of-service rate of 31.4%. The code ranks #1569 out of 3,036 FMCSR codes by citation volume, meaning it is one of the least-cited violations in the federal inspection system.
Inspection data from the last 90 days shows citations are trending stable, with no sharp spike or decline. June 2025 was the highest month at 7 citations, and most other months fell between 2 and 4 citations.
Who gets cited most
Over the last 180 days, California has the highest citation count with 9 citations and a 0.0% out-of-service rate. Washington follows with 3 citations and 0.0% OOS rate, and Arizona has 2 citations, also with 0.0% OOS rate. Oklahoma and Tennessee each recorded 1 citation in the period, both with 0.0% OOS rates.
Our data shows that across all states cited for this violation, the out-of-service rate remains uniformly at 0.0%. There is no material variation in enforcement severity by state. California's higher volume reflects the state's large trucking population and inspection frequency, not a difference in how aggressively inspectors interpret the regulation.
While all-time citation history shows that carriers such as JOSE ALFREDO AYALA have appeared in our records with citations for radar detector violations, single or low-frequency citations among small carriers or owner-operators are not unusual given the rare nature of this enforcement action.
How severe is this compared to similar codes
392.71B-MC belongs to the Unsafe Driving category. The peer code in the same category that draws the most enforcement attention is 392.2 (Operating a CMV while ill or fatigued), which has accumulated 1,208,164 citations with a 0.8% out-of-service rate. Other related variants such as 392.2-SLLSR and 392.2RG have been cited 191,232 and 96,652 times respectively, each with out-of-service rates of 0.1%.
By comparison, 392.71B-MC at 61 all-time citations is extraordinarily rare. It receives a fraction of the enforcement attention paid to fatigue and illness violations, which are cited thousands of times per month across the national system. The 0.0% out-of-service rate also indicates that inspectors and safety officials do not view confirmed radar detector violations as an immediate roadside safety threat warranting vehicle impoundment.
How to avoid it
The most direct way to avoid a 392.71B-MC citation is to ensure your carrier has a clear, documented policy prohibiting radar detectors in all company vehicles, and that this policy is communicated to every driver in writing during onboarding and in periodic safety briefings.
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Verify your carrier's radar detector policy in writing. Before you start a job or accept a load, confirm that your employer does not use, require, or permit radar detectors. Ask for the policy in writing. If your carrier has not explicitly prohibited them, request clarification in email.
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Do not carry, install, or use a radar detector. Even if your personal vehicle has one, do not transfer it to a CMV you operate for work. Removing the device eliminates the violation at the source and protects both you and your carrier.
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Report carrier pressure to use a radar detector. If a dispatcher, safety manager, or fleet owner tells you to use a radar detector or implies that one is expected, escalate it immediately to the company's compliance officer or HR. Document the conversation. A carrier-level violation may begin with driver coercion; breaking that chain protects the entire operation.
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Inspect your vehicle's equipment before every trip. During your pre-trip walkaround, visually check the windshield, dashboard, and sun visor for any radar detection equipment. If you find one installed, report it to the carrier and do not operate the vehicle until it is removed and documented as removed.
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Maintain strong communication with your carrier's safety team. Our data shows that inspections citing 392.71B-MC often co-occur with other violations such as record-of-duty-status failures (395.8A1-HOSP) and brake maintenance issues. This pattern suggests that carriers citing for radar detectors may also have gaps in other compliance areas. Engage proactively with your carrier's safety program to flag and fix compliance issues before an inspection finds them.
The rarity of this citation across 13 million inspections indicates that most carriers and drivers understand and follow this rule. Staying aware and vigilant will keep you out of the small group of operators subject to federal enforcement action for this violation.