---
kind: "section"
citation: "49 C.F.R. § 325.91"
title: "49"
number: "325.91"
heading: "Exhaust systems."
url: "https://uscodex.org/cfr/49/325.91"
---

# §325.91. Exhaust systems.


A motor vehicle does not conform to the visual exhaust system inspection requirements, [40 CFR 202.22](/cfr/40/202.22.md), 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.

## Notes

### Amendments

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

### Authority

Authority: 42 U.S.C. 4917; 49 U.S.C. 301; and 49 CFR 1.87.

### Source

Source: 40 FR 42437, Sept. 12, 1975, unless otherwise noted.

### Amendments

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