TruckCodex

393.43D-B — Brake - relay emergency valve

FMCSA violation code under Vehicle Maintenance. 14,687 events recorded in roadside inspections. Severity weight: 7.

Severity Weight
7
OOS Eligible
No
BASIC Category
Vehicle Maintenance
Total Events
14,687
Code
393.43D-B
Code System
FMCSR
BASIC Category
Vehicle Maintenance
OOS Eligible
No
Severity Weight
7
Violation Group
—
Total Events
14,687
Carriers Cited
11,672

Violation Description

Relay or emergency valve on CMV is defective or malfunctioning.

About This Violation Code

Code 393.43D-B falls under the Vehicle Maintenance BASIC category in FMCSA's Safety Measurement System (SMS). It carries a severity weight of 7 (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 393.43D in the Federal Motor Carrier Safety Regulations.

View on eCFR.gov →FMCSA Violations Search →
Events (all time)
14,687
OOS Events
14,414
OOS Rate
98.1%
Top State (180d)
Tennessee
333 events

Top Enforcing States

Where 393.43D-B is most commonly cited (last 180 days)

1.Tennessee
333
OOS 100.0%
2.Kansas
245
OOS 99.6%
3.Florida
226
OOS 100.0%
4.Pennsylvania
226
OOS 99.1%
5.Washington
223
OOS 100.0%
6.New York
218
OOS 100.0%
7.California
214
OOS 93.9%
8.Missouri
174
OOS 100.0%
9.Utah
169
OOS 100.0%
10.Maryland
157
OOS 100.0%
11.Minnesota
141
OOS 100.0%
12.Alabama
136
OOS 100.0%
13.Ohio
131
OOS 100.0%
14.Colorado
131
OOS 100.0%
15.Arizona
119
OOS 100.0%

Click a state to see roadside inspection activity, top stations, and carrier profiles in that jurisdiction.

Citation Trend (12 months)

Monthly count of 393.43D-B citations. Red bars mark months with OOS-triggering citations.

413
Apr
907
May
927
Jun
1,070
Jul
1,053
Aug
1,051
Sep
999
Oct
722
Nov
630
Dec
599
Jan
712
Feb
977
Mar
50
Apr

Most Active Stations

Inspection stations citing 393.43D-B most often (last 180 days)

1.STANTON TN
116
OOS 100.0%
2.KNOXVILLE TN
109
OOS 100.0%
3.NJ
47
OOS 100.0%
4.PA
38
OOS 94.7%
5.MAYVIEW MO
34
OOS 100.0%
6.NEOSHO COUNTY - 133
34
OOS 100.0%
7.KS
30
OOS 100.0%
8.LOMA CO
29
OOS 100.0%
9.ST. GEORGE UT
28
OOS 100.0%
10.NIMITZ IF
26
OOS 100.0%

Often Cited Together

Other violations commonly found on the same inspection (last 90 days)

393.48A-BIHE1,127 co-occurrences396.17C-PI1,023 co-occurrences392.2-SLLSR611 co-occurrences396.3A1-BOS446 co-occurrences393.95A1408 co-occurrences390.21TB2-DOT396 co-occurrences393.95F391 co-occurrences383.23A2-LCDLN331 co-occurrences393.9A-LIL323 co-occurrences390.21TB1-MC319 co-occurrences

Citation patterns suggest related root causes (e.g., HOS violations paired with logbook errors).

Top Carriers Cited

Ranked by frequency • 11,672 carriers total • Page 1 of 467

Top Carriers with 393.43D-B Violations

Showing 25 of 11,672

fmcsa-violations
Top Carriers with 393.43D-B Violations
#CarrierUSDOT# Violations
#1SAKARA LLC442953064
#2AUTO HAUL EXPRESS LLC432932558
#3SUPLICIUM TRANSPORT LLC438125554
#4HAULDEX LLC448935045
#5HORIZEN LLC440023443
#6GOLLA GROUP LLC451482030
#7PINGVIN EXPRESS LLC433525728
#8ASV XPRESS LLC438930128
#9BENNETT TRUCK TRANSPORT LLC60038224
#10CENTRAL TRANSIT SERVICES LLC444178417
#11CRYSTAL TRUCKING INC116515617
#12PALYCH TRANS LLC433576317
#13JAY TORRES LLC377915417
#14MLS CAPITAL INC364804416
#15MASTEC NETWORK SOLUTIONS239056416
#16HORIZON TRANSPORT INC27328616
#17KOOPERATIV LLC435867916
#18LADA TRANS INC299838116
#19KLU TRANS LLC426304615
#20BM CARGO INC376013115
#21FASTWAYCOMP LLC444916915
#22BETA AUTO TRANSPORT LLC433397714
#23LEASE AE LLC438632714
#24LCZW CARGO LLC449212714
#25MTMFO LLC450179814

Recent Inspections

Latest inspections where 393.43D-B was cited • 14,687 total events • Page 1 of 588

Recent Inspections with 393.43D-B

Showing 25 of 14,687

fmcsa-inspections
Recent Inspections with 393.43D-B
DateReport #StateLevelOOS
Apr 3, 202687485656MALevel 1Yes
Apr 3, 202687485692MALevel 2Yes
Apr 3, 202687484997LALevel 1Yes
Apr 3, 202687485348MOLevel 1Yes
Apr 3, 202687485066PALevel 1Yes
Apr 3, 202687484484NYLevel 1Yes
Apr 2, 202687476761MALevel 2Yes
Apr 2, 202687486723OKLevel 1Yes
Apr 2, 202687484247MOLevel 1Yes
Apr 2, 202687475700KSLevel 1Yes
Apr 2, 202687477373OKLevel 1Yes
Apr 2, 202687489562CALevel 2Yes
Apr 2, 202687488929CALevel 2Yes
Apr 2, 202687483729PALevel 1Yes
Apr 2, 202687475842ORLevel 2Yes
Apr 2, 202687480557CALevel 1Yes
Apr 1, 202687459161INLevel 2Yes
Apr 1, 202687483607TNLevel 1Yes
Apr 1, 202687469906CALevel 2Yes
Apr 1, 202687465412OKLevel 1Yes
Apr 1, 202687459453MALevel 2Yes
Apr 1, 202687459449MALevel 2Yes
Apr 1, 202687459353PALevel 2Yes
Apr 1, 202687454204CTLevel 1Yes
Apr 1, 202687459173UTLevel 1Yes

Data sources & freshness

FMCSA Vehicle Inspections and Violations
Unknown freshness
Federal Motor Carrier Safety Regulations (49 CFR)
Unknown freshness

Related records

CategoryAll Vehicle Maintenance Violations
Browse all violation codes in the Vehicle Maintenance BASIC
IndexAll Violation Codes
FMCSR violation codes by BASIC category
ReferenceFMCSA Roadside Inspections
Inspection levels and procedures
ToolSearch Carriers
Look up carriers by USDOT, name, or VIN