FMCSR 393.50B: Steering Mechanism Defective – Driver Q&A

No. Across our inspection records, 393.50B has never resulted in an out-of-service order—the OOS rate is 0.0% (0 out of 53 all-time citations). This stands in sharp contrast to the national average OOS rate of 31.4% across all FMCSR codes. While a defective steering mechanism is a serious safety issue that must be corrected, inspectors have not used out-of-service authority for this violation. You will receive a citation, but your truck will not be immediately pulled from service.

A 393.50B citation carries a CSA severity weight of 8 points. The actual impact on your Safety Management System depends on when the violation occurred and how many other violations appear on the same inspection record. CSA points accumulate over a rolling 24-month period, so context matters. Check your FMCSA Safety Management System account to see how this citation affects your specific Unsafe Driving and Vehicle Maintenance BASICs.

First, inspect your steering system thoroughly—check for broken components, loose connections, or binding that prevents smooth operation. Second, document the defect and any repairs with photos and receipts. Third, get a full pre-trip inspection from a qualified mechanic before operating again. Our data shows steering defects frequently appear alongside windshield damage (4 shared inspections in the last 90 days), inoperable lamps (4 shared), and worn steering components (2 shared), so a complete safety audit is prudent. Finally, report the repair completion to your carrier's safety manager if applicable.

Yes and no. The 393.50B OOS rate of 0.0% is significantly lower than the all-FMCSR average of 31.4%, indicating inspectors treat it as correctable rather than immediately dangerous. However, a related code—393.53B (Steering system components worn)—also carries 0.0% OOS rate and frequently co-occurs with 393.50B (2 shared inspections in 90 days). Both require prompt repair. Unlike codes such as 396.3(a)(1) (Inspection/repair/maintenance general), which has a 45.3% OOS rate, 393.50B does not typically trigger roadside vehicle removal.

Yes, you can file a DataQs (Dispute Resolution) challenge if you believe the citation was incorrect or the inspection was improper. DataQs is FMCSA's formal process for drivers and carriers to contest violations recorded in the Roadside Drug and Alcohol Testing Program database. Submit your challenge within a set window with evidence (repair receipts, pre-citation inspection records, mechanic certification) showing the steering mechanism was functioning properly or that the inspector misidentified the defect. Success depends on documentation quality, not on how common the violation is.

Over the last 180 days, Texas accounts for the vast majority of 393.50B enforcement—17 citations with a 0.0% OOS rate. Our inspection records show this code ranks #1609 out of 3,036 FMCSR codes by citation volume nationwide, making it relatively uncommon. The low national citation count (31 in the last 12 months) means you are unlikely to encounter this violation unless you operate in or through Texas or have a steering system already showing visible wear.

Fix it before your next shift. A defective steering mechanism directly impacts vehicle control and brake coordination—this is a safety-critical system. Our data shows steady enforcement momentum: 8 citations in the last 90 days, with March 2026 recording 5 citations alone, suggesting inspectors remain alert for steering defects. Even though the OOS rate is 0.0%, operating a vehicle with a known steering defect exposes you to liability, repeat citations, and potential DOT violations. Repair immediately and document the work.

Freightliner units lead the citation count with 14 all-time citations for 393.50B, followed by Kenworth (10 citations) and Mack (9 citations). International and Peterbilt each account for 6 citations. These figures represent our inspection database and may reflect overall fleet composition rather than inherent reliability differences. If you operate a Freightliner or Kenworth, routine steering system inspection should be part of your preventive maintenance program.