CDL Restriction Codes Explained

The federal restriction codes

49 CFR 383.153(a)(10) lists the standard restriction codes a CDL can carry:

• L: no air brake equipped CMV
• Z: no full air brake equipped CMV
• E: no manual transmission equipped CMV
• O: no tractor-trailer CMV
• M: no Class A passenger vehicle
• N: no Class A and B passenger vehicle
• K: intrastate only
• V: medical variance

Why a restriction gets added

Most restrictions are a direct result of the vehicle you test in, and 49 CFR 383.95 spells out each trigger. States must add the restriction if the license is issued.

• L: you fail the air brake part of the knowledge test, or take the skills test in a vehicle with no air brakes (383.95(a)). Air brakes here means any system working fully or partly on the air brake principle.
• Z: you take the skills test in a vehicle with air over hydraulic brakes. You are barred from vehicles with brakes operating fully on the air brake principle (383.95(b)).
• E: you take the skills test in a vehicle with an automatic transmission (383.95(c)). The definition in 383.5 counts any transmission other than a driver-operated clutch and gear shift as automatic, including semi-automatic.
• O: you take the Group A skills test in a combination connected by a pintle hook or other non-fifth-wheel connection (383.95(d)). You then cannot drive a fifth-wheel tractor-trailer that needs a Group A CDL.
• M and N: you take the passenger endorsement skills test in a smaller passenger vehicle, so you are barred from larger passenger vehicles (383.95(e) and (f)).
• V: the state is notified that you were issued a medical variance (383.95(g)).

Failing the air brake knowledge test

This one catches people on the written test, not the road. Under 49 CFR 383.135(a)(2), if you score under 80 percent on the air brake portion and a CLP or CDL is issued anyway, it carries the air brake restriction. That restriction applies to any CMV with air brakes. It rules out most tractor-trailers and many straight trucks, so for most drivers it is worth retaking the test.

How to remove one

49 CFR 383.135(b)(7) covers the air brake, full air brake and manual transmission restrictions. You do not have to retake the whole skills test. The state may give you a modified skills test showing you can safely operate the vehicle's full air brakes, air over hydraulic brakes, or manual transmission. To remove the air brake or full air brake restriction you must also successfully perform the air brake pre-trip inspection and pass the air brake knowledge test. The tractor-trailer (O) restriction is different. 383.135(b)(8) says you must retake all three skills tests in a representative tractor-trailer. Federal rule exempts people removing a restriction from the entry-level driver training requirement (49 CFR 380.603(a)(4)). The modified test itself, the fee and the appointment process are set by your state.

States can add their own codes

The federal list is a minimum, not a ceiling. 49 CFR 383.153(a)(10)(ix) lets a state add extra restriction codes at its discretion, as long as each is explained on the front or back of the license. A code on your license that is not in the list above is a state code. For a permit, 383.153(b)(2)(ix) has its own list: P (no passengers in a CMV bus), X (no cargo in a CMV tank vehicle), L, V, M, N and K, plus any additional jurisdictional restrictions. To see what a particular code means and how your state removes it, ask your state licensing agency.