What 392.2DIM means in plain language
FMCSR 392.2DIM addresses a fundamental safety rule: you cannot operate a commercial motor vehicle if your ability or alertness is impaired by fatigue, illness, or any other condition that makes it unsafe to drive. This is not about being tired at the end of a long day—it's about being so impaired that continuing to operate the vehicle creates a safety hazard.
The rule covers a broad range of impairment sources. Illness—whether a cold, flu, migraine, or a condition that impairs judgment or reaction time—counts. Fatigue from lack of sleep or inadequate rest counts. Medical events, medication side effects, or untreated pain that affects your ability to control the vehicle counts. The key question inspectors and prosecutors ask is whether your condition made it unsafe for you to begin or continue operating.
What makes this citation different from a warning is that an inspector has documented observable signs: erratic driving, crossing lane lines, slow reaction at a weigh station, nodding off, slurred speech, or self-reported exhaustion or illness. The citation reflects a decision that you should have pulled over and rested, not continued down the road.
What our enforcement data actually shows
Across our 13 million+ inspection records, we have documented 2,019 all-time citations for 392.2DIM. In the last 12 months, enforcement volume was 826 citations, and in the last 90 days, 178 citations were issued. This ranks 392.2DIM as the #536 most-cited code out of 3,036 FMCSR codes—relatively uncommon but not rare.
The out-of-service (OOS) rate for this violation is 0.8%. That means only 17 of the 2,019 citations resulted in the driver being placed out of service; 2,002 were handled as violations without an immediate OOS order. This OOS rate is substantially lower than the all-FMCSR average of 31.4%, indicating that inspectors typically view 392.2DIM as a correctable behavior rather than an immediate safety emergency that requires pulling the truck off the road on the spot.
Monthly citation counts over the past 12 months ranged from a low of 32 citations (April 2025) to a high of 98 citations (March 2026), with most months falling in the 60–80 citation range. The low OOS count remained consistent: across all 12 months, only 6 out-of-service placements occurred in total, concentrated in May (3) and June (2) of 2025.
Who gets cited most
Our inspection records show that Iowa leads enforcement by a significant margin. Over the last 180 days, Iowa accounted for 247 citations—nearly 4 times the second-place state. Illinois follows with 66 citations, and North Carolina third with 40 citations. Notably, across all three of these top enforcement states, the OOS rate was 0.0%. No driver cited in Iowa, Illinois, or North Carolina for 392.2DIM in the past 180 days was placed out of service, consistent with the national 0.8% OOS rate for this code.
Among carriers with the highest citation counts in our database, Heavy Haul Transport LLC (USDOT 3507944) recorded 18 citations and D&D Transporting LLC (USDOT 3106896) recorded 11 citations. These numbers reflect the enforcement frequency within those fleets' operations and may relate to operational patterns, driver population size, or inspection frequency rather than indicating systemic safety negligence.
How severe is this compared to similar codes
392.2DIM belongs to a large family of related fatigue and illness violations under the 392.2 umbrella. The parent code 392.2 itself has accumulated 1,208,164 citations across all time with a 0.8% OOS rate—identical to 392.2DIM's rate. Other closely related variants show similar enforcement patterns: 392.2RG has 96,652 citations with a 0.1% OOS rate, and 392.2-SLLEWA1 has 69,565 citations with a 1.0% OOS rate.
The code with the highest OOS rate in the family is 392.2-SLLEQP, at 2.4%, which suggests that subset of fatigue/illness violations involves more imminent danger. By contrast, 392.2DIM's 0.8% OOS rate sits at the lower end of severity within its peer group, consistent with the observation that inspectors treat these citations as correctable violations in most cases.
How to avoid it
Our data on co-occurring violations and vehicle patterns offers concrete guidance. Several preventive actions will reduce your risk:
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Sleep and rest before departing. The most direct way to avoid this citation is to ensure you are genuinely rested before you start your shift. If you have slept fewer than 5 hours, or if you know you were awake more than 18 hours before your trip, delay departure. A citation or roadside inspection delay costs far more time than a short nap.
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Recognize and act on illness signals early. If you develop a headache, fever, dizziness, or medication side effects during a shift, do not push through. Pull into a safe location, rest, or find another driver. Our data shows 29 inspections in the last 90 days included both 392.2DIM and co-occurring 392.2RG violations, suggesting that multiple fatigue or illness indicators were visible to inspectors.
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Check your vehicle's safety systems before each trip. Co-occurring violations in our data include 393.9 (inoperable required lamp), 393.95A (missing fire extinguisher), and 396.17C (no proof of periodic inspection) in 15, 14, and 18 shared inspections respectively. Inspectors who stop you for a safety system defect may also observe fatigue or illness signs. A pre-trip inspection that catches brake lights, emergency equipment, and vehicle documentation issues may prevent the stop altogether.
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Build alertness checks into your route. If you feel any drowsiness, impaired judgment, or physical weakness during a long drive, stop at a safe location and rest. Most citations for this code result from erratic driving that prompted the stop—not from proactively reporting yourself as fatigued.
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Be transparent if you are unwell. If an inspector asks whether you are feeling okay, answer honestly. Fatigue and illness are not character flaws; they are safety facts. An honest conversation with an inspector about your condition and a decision to rest may prevent a citation and will certainly prevent a crash.
The 0.8% OOS rate on this violation suggests that most drivers cited are allowed to rest and continue after documenting the violation. Taking the preventive step of resting before you feel unsafe keeps you and others safe and keeps your record clear.