What 392.71A-D means in plain language
FSMCSR 392.71A-D prohibits drivers from using radar detectors in commercial motor vehicles or equipping their CMV to have one installed. This applies whether the device is actively being used during operation or simply present in the cab.
The regulation treats radar detectors as safety equipment violations. The federal standard applies uniformly across all 50 states, though individual states may have their own additional restrictions on radar detectors for non-commercial vehicles.
If an officer observes a radar detector mounted on your dashboard, wired to your power system, or even loose in your cab during a roadside inspection, they can cite you under this code. The citation does not require that you were actively using the device to detect speed enforcement—its mere presence is enough.
What our enforcement data actually shows
Across our 13 million+ inspection records, we have documented 2,280 all-time citations for 392.71A-D, making it ranked 507th of 3,036 FMCSR codes by citation volume. In the last 12 months, enforcement officers issued 1,332 citations for this violation, with 262 citations recorded in the last 90 days.
Critically, our data shows that 392.71A-D citations have a 0.0% out-of-service rate—no vehicles were placed out of service in any of the 2,280 inspections in our database. This is substantially lower than the all-FMCSR average OOS rate of 31.4%. This means while the violation is enforceable, it does not result in immediate roadside removal of your vehicle.
Enforcement activity has been steady. Our monthly trend data over the last 12 months shows citations ranging from a low of 34 in April 2025 to a peak of 164 in July 2025, indicating enforcement pressure fluctuates seasonally but remains consistent year-round.
Who gets cited most
Citations for 392.71A-D are geographically concentrated. Over the last 180 days, our inspection records show the top three states by citation count are California with 132 citations, Arizona with 121 citations, and Washington with 34 citations. All three states have recorded 0.0% out-of-service rates for this code—enforcement is citation-only in these jurisdictions.
Other states with significant enforcement volume include Oregon with 21 citations, Indiana with 20 citations, and Kansas with 19 citations. No material variation in OOS rates exists across these states; enforcement across the country treats radar detector violations as non-removal offenses.
Our data shows fleets such as United Parcel Service Inc with 8 all-time citations for this code. Enforcement is distributed across many small and mid-size carriers, indicating the violation is not concentrated in any single fleet segment.
How severe is this compared to similar codes
Radar detector violations sit in the Unsafe Driving category alongside several other behavioral codes. By comparison, 392.2 (Operating a CMV while ill or fatigued) has 1,208,164 all-time citations with a 0.8% OOS rate—far higher enforcement volume but comparable low removal rates. The 392.2-SLLTCD variant shows 85,391 citations with a 0.0% OOS rate, identical to 392.71A-D's enforcement profile.
The 392.2-SLLSR code variant has 191,232 citations with only 0.1% OOS rate, showing that many Unsafe Driving violations result in citations without roadside vehicle removal. In contrast, 392.2-SLLEQP (a fatigue-related code) shows 72,352 citations but a notably higher 2.4% OOS rate, demonstrating that some unsafe driving violations carry greater severity.
Radar detector citations are firmly in the low-severity enforcement tier—citation-only, no vehicle removal, and rarely escalated.
How to avoid it
The straightforward path to avoid 392.71A-D citations is simple: do not install, mount, or carry a radar detector in your CMV. Before your next pre-trip inspection, verify your cab interior and eliminate any radar detection equipment.
Our inspection records reveal patterns in co-occurring violations. When 392.71A-D citations appear alongside other code violations, they most often co-occur with 396.17C-PI (no proof of periodic inspection) in 37 shared inspections over the last 90 days, 395.8A1-HOSP (hours-of-service record-keeping failures) in 30 shared inspections, and 392.2-SLLSR (operating while ill or fatigued) in 29 shared inspections. This clustering suggests that drivers cited for radar detectors are sometimes already operating with other safety or compliance gaps. A thorough pre-trip that includes verifying your maintenance logs and rest-of-duty status documentation may prevent a cascade of citations if you are stopped.
Second, conduct a cab walk-around before each shift. The top vehicle makes cited for this code—Freightliner (409 citations), Kenworth (209 citations), and Peterbilt (201 citations)—are common models with aftermarket electronic installations. Check under the dashboard, behind the sun visor, and near the windshield for any mounted or hardwired radar detection hardware. Even devices left by a previous driver or owner can result in a citation.
Third, if you are operating a leased or used vehicle, confirm with your carrier or the previous operator that no radar detection equipment remains installed. Carriers are responsible for fleet equipment compliance, but drivers are cited at the roadside.
Finally, maintain documentation of your vehicle's equipment. If an officer cites you and questions whether the device was factory-installed or aftermarket, having service records or pre-assignment inspection photos can help clarify the timeline and may support disputes if the device was installed without your knowledge.