§FMCSR.com
Historical textIn force on Sept. 30, 2011Source: annual CFR edition 2010

§ 325.91 Exhaust systems.

Wording in the annual edition revised as of Oct. 1, 2010, superseded by the 2011 annual edition.

govinfo, 2010 edition ↗
Before Jan. 1, 2017 the record is one snapshot per annual CFR edition, revised as of October 1. This is the 2010 edition's wording. An amendment that took effect between Oct. 1, 2010 and Sept. 30, 2011 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 September 30, 2011. This wording effective October 1, 2010 to October 1, 2011. Source: govinfo, 2010 edition, https://www.govinfo.gov/app/details/CFR-2010-title49-vol5/CFR-2010-title49-vol5-sec325-91. Retrieved from FMCSR.com, https://fmcsr.com/reg/325.91?asof=2011-09-30, on October 26, 2026. Unofficial compilation; verify against the official source.

Link to an amendment published at 75 FR 57193, Sept. 20, 2010.

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.

Effective Date Note:

At 75 FR 57193, Sept. 20, 2010, § 325.91 was amended by revising paragraph (b), effective November 19, 2010. For the convenience of the user, the revised text is set forth as follows:

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. previousviewing
  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.