§FMCSR.com
Current textIn force on Oct. 1, 2013Source: annual CFR editions 2011–2016

§ 325.91 Exhaust systems.

Current wording, in the annual edition revised as of Oct. 1, 2011.

govinfo, 2013 edition ↗
Before Jan. 1, 2017 the record is one snapshot per annual CFR edition, revised as of October 1. This is the 2013 edition's wording. An amendment that took effect between Oct. 1, 2013 and Oct. 1, 2013 would not appear until the next edition, so check the citations below and the Federal Register for exact effective dates.
49 CFR § 325.91 — Exhaust systems.. Text in force on October 1, 2013. This wording effective October 1, 2011 to present. Source: govinfo, 2013 edition, https://www.govinfo.gov/app/details/CFR-2013-title49-vol5/CFR-2013-title49-vol5-sec325-91. Retrieved from FMCSR.com, https://fmcsr.com/reg/325.91?asof=2013-10-01, on October 26, 2026. Unofficial compilation; verify against the official source.

A motor vehicle does not conform to the visual exhaust system inspection requirements, 40 CFR 202.22, of the Interstate Motor Carrier Noise Emission Standards, if inspection of the exhaust system of the motor vehicle discloses that the system—

(a) Has a defect which adversely affects sound reduction, such as exhaust gas leaks or alteration or deterioration of muffler elements, (small traces of soot on flexible exhaust pipe sections shall not constitute a violation of this subpart);

(b) Is not equipped with either a muffler or other noise dissipative device; or

(c) Is equipped with a cut-out, by-pass, or similar device, unless such device is designed as an exhaust gas driven cargo unloading system.

[40 FR 42437, Sept. 12, 1975, as amended at 75 FR 57193, Sept. 20, 2010]

Amendment history

3 distinct wordings on file since Oct. 1, 1996
  1. Oct. 1, 2011 → presentannual editions 2011–2016diff vs. previousviewing
    [40 FR 42437, Sept. 12, 1975, as amended at 75 FR 57193, Sept. 20, 2010]
  2. Oct. 1, 2010 → Oct. 1, 2011annual edition 2010diff vs. previous
  3. Oct. 1, 1996 → Oct. 1, 2010annual editions 1996–2009

A new entry appears whenever the regulatory words change between government snapshots. Day-precise from the eCFR (2017 onward); before that, one snapshot per annual CFR edition (revised as of October 1). Bracketed citations are the Federal Register history printed with the section.