FMCSR 393.43(c) — Brake Relay Emergency Valve | Q&A

No. Across our 13 million+ inspection records, a 393.43(c) citation for a defective or malfunctioning relay or emergency valve has never resulted in an out-of-service order—the OOS rate is 0.0%. All 23 citations on record were issued as non-OOS violations. However, this does not mean the defect is minor; it means inspectors typically document the finding and allow you to schedule repairs rather than immediately sidelining the vehicle.

A 393.43(c) citation carries a severity weight of 7 CSA points. Under the FMCSA Safety Management Guidelines, this violation is attributed to your Safety and Fitness Electronic Subrogation (SAFER) profile within 30 days of the citation. The points contribute to your carrier's Vehicle Maintenance BASIC score; accumulating violations in this category can increase your crash risk profile and trigger compliance investigations.

First: Document the citation details (date, location, inspector name, badge number). Second: Have a qualified diesel mechanic inspect the relay or emergency valve system within 48 hours to confirm the defect. Third: Schedule repair with your carrier's maintenance team or an authorized shop. Fourth: Keep all repair receipts and work orders. Fifth: Request a follow-up inspection once repairs are complete to clear the violation from your record. Do not ignore the citation—even though it's not OOS-eligible, unaddressed brake system defects are safety risks and can lead to more severe findings.

In context, 393.43(c) is rare and less likely to trigger out-of-service action. Our database shows 393.43(c) ranks #1881 out of 3,036 FMCSR codes by citation frequency, with only 23 all-time citations and zero enforcement in the last 12 months. By contrast, the peer code 393.47E (slack adjuster defective) has 180,363 citations, and 393.9(a) (inoperable lamps) has 660,737. Your OOS rate of 0.0% is significantly better than the national all-FMCSR average of 31.4%, though brake-related defects always carry safety weight.

Yes. You can challenge the citation through the FMCSA's Record Dispute Resolution (DataQs) system within the statute of limitations (generally 90 days) of the inspection. Request your roadside inspection report and photographs from the inspector. If the inspector did not document the specific malfunction (e.g., no description of valve response, pressure readings, or symptom observed), you have grounds to dispute. Equipment-based findings are easier to contest if the mechanic's follow-up inspection shows the component functioning correctly. Submit your rebuttal with repair receipts or a clean reinspection report to support your case.

This violation is extremely rare and not trending upward. Our inspection records show zero citations for 393.43(c) in the last 90 days and zero in the last 12 months, despite 13 million+ total records in the database. The 23 all-time citations span years of enforcement history, indicating that relay and emergency valve defects are caught infrequently relative to other brake system violations. This suggests either strong preventive maintenance across the fleet or that the issue is typically caught under different violation codes.

Across our inspection records, FORD vehicles account for 7 of the 23 citations (30%), followed by DODGE with 5 citations (22%) and CHEVROLET and UNPUBLISHED makes tied at 4 citations each (17%). The remaining citations are scattered among GMC, BIG TEX trailers, and international makes. This distribution reflects the prevalence of Ford and Dodge platforms in small-to-medium fleet and owner-operator operations rather than a systematic defect in any single manufacturer's relay valve design.

A 393.43(c) citation is recorded against both the driver and the carrier in the FMCSA Safety and Fitness Electronic Subrogation (SAFER) system. The violation contributes to your carrier's Vehicle Maintenance BASIC safety metric and appears on roadside inspection histories. If you change carriers, the citation remains on your personal inspection record. However, the CSA severity weight (7 points) is typically attributed to the carrier's fleet performance; your individual CSA profile is weighted differently than your carrier's.