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40 CFR § 1065.303 - Summary of required calibration and verifications. 

---
identifier: "/us/cfr/t40/s1065.303"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 1065.303 - Summary of required calibration and verifications."
title_number: 40
title_name: "Protection of Environment"
section_number: "1065.303"
section_name: "Summary of required calibration and verifications."
chapter_name: "ENVIRONMENTAL PROTECTION AGENCY"
subchapter_number: "U"
subchapter_name: "AIR POLLUTION CONTROLS"
part_number: "1065"
part_name: "ENGINE-TESTING PROCEDURES"
positive_law: false
currency: "2026-03-24"
last_updated: "2026-03-24"
format_version: "1.1.0"
generator: "[email protected]"
authority: "42 U.S.C. 7401-7671q."
regulatory_source: "70 FR 40516, July 13, 2005, unless otherwise noted."
cfr_part: "1065"
---

# 1065.303 Summary of required calibration and verifications.

The following table summarizes the required and recommended calibrations and verifications described in this subpart and indicates when these have to be performed:

Table 1 of § 1065.303—Summary of Required Calibration and Verifications

| Type of calibration or verification | Minimum frequency |
| --- | --- |
| § 1065.305: Accuracy, repeatability and noise | Not required, but recommended for initial installation. Repeatability: Not required, but recommended for initial installation. |
|  | Not required, but recommended for initial installation. |
| § 1065.307: Linearity verification |  |
|  | Upon initial installation, within 370 days before testing and after major maintenance. |
|  | Upon initial installation, within 370 days before testing and after major maintenance. |
|  | Upon initial installation, within 370 days before testing and after major maintenance. |
|  | Upon initial installation, within 370 days before testing, and after major maintenance. |
|  | Upon initial installation, within 370 days before testing, and after major maintenance. |
|  | Upon initial installation, within 370 days before testing, and after major maintenance. |
|  | Upon initial installation, within 370 days before testing, and after major maintenance. |
|  | Upon initial installation, within 370 days before testing and after major maintenance. |
|  | Upon initial installation, within 185 days before testing and after major maintenance. |
|  | Upon initial installation, within 370 days before testing, and after major maintenance. |
|  | Upon initial installation, within 35 days before testing and after major maintenance. |
|  | Upon initial installation, within 370 days before testing and after major maintenance. |
|  | Upon initial installation and after major maintenance. |
|  | Upon initial installation, within 370 days before testing and after major maintenance. |
|  | Upon initial installation, within 370 days before testing and after major maintenance. |
| § 1065.308: Continuous gas analyzer system response and updating-recording verification—for gas analyzers not continuously compensated for other gas species | Upon initial installation or after system modification that would affect response. |
| § 1065.309: Continuous gas analyzer system-response and updating-recording verification—for gas analyzers continuously compensated for other gas species | Upon initial installation or after system modification that would affect response. |
| § 1065.310: Torque | Upon initial installation and after major maintenance. |
| § 1065.315: Pressure, temperature, dewpoint | Upon initial installation and after major maintenance. |
| § 1065.320: Fuel flow | Upon initial installation and after major maintenance. |
| § 1065.325: Intake flow | Upon initial installation and after major maintenance. |
| § 1065.330: Exhaust flow | Upon initial installation and after major maintenance. |
| § 1065.340: Diluted exhaust flow (CVS) | Upon initial installation and after major maintenance. |
| § 1065.341: CVS and PFD flow verification (propane check) | Upon initial installation, within 35 days before testing, and after major maintenance. |
| § 1065.342 Sample dryer verification | For thermal chillers: Upon installation and after major maintenance. For osmotic membranes; upon installation, within 35 days of testing, and after major maintenance. |
| § 1065.345: Vacuum leak | For laboratory testing: Upon initial installation of the sampling system, within 8 hours before the start of the first test interval of each duty-cycle sequence, and after maintenance such as pre-filter changes. |
|  | For field testing: After each installation of the sampling system on the vehicle, prior to the start of the field test, and after maintenance such as pre-filter changes. |
| § 1065.350: CO NDIR H O interference | Upon initial installation and after major maintenance. |
| § 1065.355: CO NDIR CO and H O interference | Upon initial installation and after major maintenance. |
| § 1065.360: FID calibration THC FID optimization, and THC FID verification | Calibrate all FID analyzers: upon initial installation and after major maintenance. |
|  | Optimize and determine CH response for THC FID analyzers: upon initial installation and after major maintenance. |
|  | Verify CH response for THC FID analyzers: upon initial installation, within 185 days before testing, and after major maintenance. |
|  | Verify C H response for THC FID analyzers if used for NMNEHC determination: upon initial installation, within 185 days before testing, and after major maintenance. |
| § 1065.362: Raw exhaust FID O interference | For all FID analyzers: upon initial installation, and after major maintenance. |
|  | For THC FID analyzers: upon initial installation, after major maintenance, and after FID optimization according to § 1065.360. |
| § 1065.365: Nonmethane cutter penetration | Upon initial installation, within 185 days before testing, and after major maintenance. |
| § 1065.366: Interference verification for FTIR analyzers | Upon initial installation and after major maintenance. |
| § 1065.369: H O, CO, and CO interference verification for ethanol photoacoustic analyzers | Upon initial installation and after major maintenance. |
| § 1065.370: CLD CO and H O quench | Upon initial installation and after major maintenance. |
| § 1065.372: NDUV HC and H O interference | Upon initial installation and after major maintenance. |
| § 1065.375: N O analyzer interference | Upon initial installation and after major maintenance. |
| § 1065.376: Chiller NO penetration | Upon initial installation and after major maintenance. |
| § 1065.378: NO-to-NO converter conversion | Upon initial installation, within 35 days before testing, and after major maintenance. |
| § 1065.390: PM balance and weighing | Independent verification: Upon initial installation, within 370 days before testing, and after major maintenance. |
|  | Zero, span, and reference sample verifications: Within 12 hours of weighing, and after major maintenance. |
| § 1065.395: Inertial PM balance and weighing | Independent verification: Upon initial installation, within 370 days before testing, and after major maintenance. |
|  | Other verifications: Upon initial installation and after major maintenance. |
| Perform calibrations and verifications more frequently than we specify, according to measurement system manufacturer instructions and good engineering judgment. |  |
| Perform linearity verification either for electrical power or for current and voltage. |  |
| Linearity verification is not required if DEF flow rate comes directly from the ECM signal as described in § 1065.247(b). |  |
| Linearity verification is not required if the flow signal's accuracy is verified by carbon balance error verification as described in § 1065.307(e)(5) or a propane check as described in § 1065.341. |  |
| CVS and PFD flow verification (propane check) is not required for measurement systems verified by linearity verification as described in § 1065.307 or carbon balance error verification as described in § 1065.341(h). |  |

[86 FR 34536, June 29, 2021]