Get direct answers on FMCSR 393.79 citations: OOS risk, CSA points, top enforcement states, and what to do after being cited.
Ranks #390 of 3,146 FMCSR codes by citation frequency • OOS rate of 0.0% is below the FMCSR-wide average of 33.3%.
Defroster/Defogger - Inoperative or defective
Direct answers grounded in TruckCodex inspection data
No. FMCSR 393.79 is not an out-of-service eligible violation. Across all 4,065 citations in our inspection records, only 1 vehicle was ever placed out of service — giving this code a 0.0% OOS rate. That single case is effectively a data anomaly. You will keep rolling after the inspection, but the citation still hits your CSA record, so ignoring the repair is not a smart play. Fix the defroster or defogger before your next inspection.
The severity weight for 393.79 is not published in our current data block, so a precise point value cannot be stated here. What we can tell you is that 393.79 falls under the Vehicle Maintenance BASIC. Citations recorded within the most recent 6 months carry the highest time-weight multiplier in the CSA scoring system, and violations from 7–12 months ago carry a lower multiplier. With 1,748 citations issued just in the last 12 months, inspectors are actively writing this code — meaning fresh citations are actively aging into carriers' and drivers' scores right now.
Get the defroster or defogger repaired and document it immediately. Here's what the co-occurring violation pattern suggests you should also check:
Repair, photograph, and retain records before your next dispatch.
Less serious than most, but not ignorable. The all-FMCSR average OOS rate across our database is 31.4%. FMCSR 393.79 sits at 0.0% — well below that benchmark. For context, peer codes in the same Vehicle Maintenance category carry significantly higher OOS exposure: 396.3(a)(1) has a 45.3% OOS rate across 236,919 citations, and 393.9(a) hits a 15.4% rate across 660,737 citations. So 393.79 won't park your truck, but it still ranks #381 out of 3,036 FMCSR codes by citation volume — meaning it gets written often enough that inspectors clearly look for it.
Yes, you can submit a challenge through FMCSA's DataQs system, but success depends on what you're disputing. If the defroster or defogger was actually functional at the time of inspection, you can request a review and provide documentation — repair records, post-trip inspection logs, or a mechanic's written verification. Since 393.79 is an equipment condition finding rather than a documentation violation, the stronger your physical evidence (photos, dated repair invoices), the better positioned your challenge will be. Submit through the FMCSA DataQs portal and keep copies of everything you upload.
Texas leads by a wide margin. Our inspection records for the last 180 days show TX with 614 citations — more than six times the next highest state. Arizona is second at 101 citations, followed by California at 44. Connecticut rounds out the notable group with 21 citations. All four of these states recorded a 0.0% OOS rate for this code, so enforcement is active but not resulting in parked trucks. If your lanes run through Texas or Arizona in particular, expect this item to be on inspectors' radar.
Don't wait. Even though the OOS rate is 0.0%, citation volume is climbing. Our inspection records show a clear upward trend: citations jumped from 45 in April 2025 to a peak of 220 in March 2026, with 173–205 citations recorded in several recent months. That means enforcement attention on this defect has intensified significantly over the past year. With 474 citations written in just the last 90 days, inspectors are actively flagging inoperative defrosters. Every inspection you run with a broken unit is an exposure you don't need.
Both can be affected. Under FMCSA's CSA methodology, vehicle maintenance violations like 393.79 are attributed to the carrier's Vehicle Maintenance BASIC. However, the driver who was operating the vehicle at the time of the inspection also receives a record of the violation tied to their CDL. Carriers accumulate these findings across all drivers and vehicles, which affects their Safety Measurement System percentile. Drivers carry the inspection history on their PSP (Pre-Employment Screening Program) record. One citation hits both sides of the ledger.
Where 393.79 is most commonly cited (last 180 days)
Other violations commonly found on the same inspection (last 90 days)
TruckCodex aggregates official public-sector datasets. See the Source registry for dataset-level coverage and the Freshness log for last-import timestamps.
Census, SAFER, SMS, Licensing & Insurance (L&I), roadside inspections, crashes, and authority history.
Vehicle recall campaigns, defect investigations, and consumer safety complaints (SCRS).
Cross-border carrier registry and Canadian recall campaigns where applicable.
TruckCodex is an independent aggregator; it is not affiliated with FMCSA, NHTSA, EIA, or Transport Canada. Always verify compliance-critical information directly with the originating agency.