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AhaBulb: Stuff Everyone Should Know · ahabulb.com/cdl-restriction-l-no-air-brakes

What happens if you fail the air brake knowledge test or take your skills test in a truck without air brakes?

Your CDL gets an air brake restriction (code L).

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  1. You cannot get a CDL at all
  2. You must wait 60 days to retest
  3. Your CDL is restricted from air brake vehicles ✔

Why: The state must mark the license so you may not drive any CMV with air brakes. The code for this is L. You can remove it later by passing the test.

Huh, didn't know that: Air over hydraulic brakes count too: they partly work on the air brake principle.

The dad joke
Why did the air brake get a promotion? It handled pressure so well.
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References

Answer: Your CDL is restricted from air brake vehicles. The state must mark the license so you may not drive any CMV with air brakes. The code for this is L. You can remove it later by passing the test.

  1. 49 CFR 383.95 Restrictions (eCFR) www.ecfr.gov/current/title-49/section-383.95
    restricted from operating a CMV equipped with any type of air brakes
    Checked 2026-10-10.
  2. 49 CFR 383.153 Information on the CLP and CDL documents (eCFR) www.ecfr.gov/current/title-49/section-383.153
    L for No Air brake equipped CMV
    Checked 2026-10-10.

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