393.77 — Heater defective or missing
FMCSA violation code under Vehicle Maintenance. 41 events recorded in roadside inspections. Severity weight: 2.
Violation Description
Heating system on commercial motor vehicle used to heat the cab or body is not operative or malfunctioning.
About This Violation Code
Code 393.77 falls under the Vehicle Maintenance BASIC category in FMCSA's Safety Measurement System (SMS). It carries a severity weight of 2 (scale 1-10, higher = more severe).
When this violation is cited during a roadside inspection, it contributes to the carrier's Vehicle Maintenance BASIC score. Carriers with high BASIC percentiles may be prioritized for FMCSA interventions including warning letters, investigations, or compliance reviews.
Regulatory Reference
Federal Motor Carrier Safety Regulations
This violation references 49 CFR 393.77 in the Federal Motor Carrier Safety Regulations.
Top Enforcing States
Where 393.77 is most commonly cited (last 180 days)
Click a state to see roadside inspection activity, top stations, and carrier profiles in that jurisdiction.
Citation Trend (12 months)
Monthly count of 393.77 citations. Red bars mark months with OOS-triggering citations.
Most Active Stations
Inspection stations citing 393.77 most often (last 180 days)
Top Carriers Cited
Ranked by frequency • 37 carriers total • Page 1 of 2
Top Carriers with 393.77 Violations
Showing 25 of 37
Recent Inspections
Latest inspections where 393.77 was cited • 41 total events • Page 1 of 2
Recent Inspections with 393.77
Showing 25 of 41
| Date | Report # | State | Level | OOS |
|---|---|---|---|---|
| Dec 31, 2025 | 86696720 | TX | Level 2 | No |
| Dec 19, 2025 | 86668168 | TX | Level 2 | No |
| Apr 23, 2025 | 84488177 | MS | Level 1 | No |
| Mar 25, 2025 | 84247491 | TX | Level 2 | No |
| Mar 21, 2025 | 84230110 | TX | Level 1 | No |
| Mar 19, 2025 | 84183857 | TX | Level 1 | No |
| Mar 19, 2025 | 84193343 | TX | Level 1 | No |
| Mar 15, 2025 | 84170614 | TX | Level 2 | No |
| Feb 17, 2025 | 83931430 | IL | Level 1 | No |
| Jan 25, 2025 | 83731165 | TX | Level 2 | No |
| Jan 22, 2025 | 83718871 | TX | Level 1 | No |
| Jan 20, 2025 | 83683768 | TX | Level 1 | No |
| Jan 13, 2025 | 83602600 | TX | Level 1 | No |
| Jan 10, 2025 | 83592987 | TX | Level 1 | No |
| Jan 9, 2025 | 83567887 | TX | Level 1 | No |
| Jan 8, 2025 | 83556570 | NE | Level 2 | No |
| Jan 7, 2025 | 83614891 | TX | Level 1 | No |
| Jan 6, 2025 | 84353540 | TX | Level 1 | No |
| Dec 6, 2024 | 83389922 | TX | Level 1 | No |
| Sep 24, 2024 | 82758011 | MI | Level 2 | No |
| Apr 2, 2024 | 81243417 | CT | Level 5 | No |
| Mar 25, 2024 | 81200767 | TX | Level 1 | No |
| Mar 19, 2024 | 81131444 | CT | Level 5 | No |
| Mar 18, 2024 | 81143494 | TX | Level 1 | No |
| Mar 16, 2024 | 81131383 | TX | Level 2 | No |