# Improvements for Heavy-Duty Engine and Vehicle Test Procedures, and Other Technical Amendments
> **Rule** · — · Published 2021-09-23 · 86 FR 52833
## Document
- **Document number:** C1-2021-05306
- **Category:** other
- **Federal Register citation:** 86 FR 52833
- **CFR reference:** 40 CFR 9
- **Publication date:** 2021-09-23
- **EPA docket:** EPA-HQ-OAR-2019-0307
## Source
- [Federal Register document](https://www.federalregister.gov/documents/2021/09/23/C1-2021-05306/improvements-for-heavy-duty-engine-and-vehicle-test-procedures-and-other-technical-amendments)
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*MORVS · CC0 1.0*