§FMCSR.com
Historical textIn force on Oct. 1, 2002Source: annual CFR editions 1996–2009

§ 325.91 Exhaust systems.

Wording first on file in the 1996 annual edition, superseded by the 2010 annual edition.

govinfo, 2002 edition ↗
Before Jan. 1, 2017 the record is one snapshot per annual CFR edition, revised as of October 1. This is the 2002 edition's wording. An amendment that took effect between Oct. 1, 2002 and Oct. 1, 2002 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, 2002. This wording effective October 1, 1996 to October 1, 2010. Source: govinfo, 2002 edition, https://www.govinfo.gov/app/details/CFR-2002-title49-vol4/CFR-2002-title49-vol4-sec325-91. Retrieved from FMCSR.com, https://fmcsr.com/reg/325.91?asof=2002-10-01, 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, such as a turbocharger (supercharger driven by exhaust gases); 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.

Amendment history

3 distinct wordings on file since Oct. 1, 1996
  1. Oct. 1, 2011 → presentannual editions 2011–2016diff vs. previous
    [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 1996–2009viewing

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.