40 CFR § 86.1925 - What records must I keep?
(a) Organize and maintain your records as described in this section. We may review your records at any time, so it is important to keep required information readily available.
(b) Keep the following paper or electronic records of your in-use testing for five years after you complete all the testing required for an engine family:
(2) Keep any additional records, including forms you create, related to any of the following:
(ii) Pre-test maintenance and adjustments to the engine performed under § 86.1910.
(iii) Test results for all void, incomplete, and voluntary testing described in § 86.1920.
(iv) Evaluations to determine why a vehicle failed the vehicle-pass criteria described in § 86.1912.
(3) Keep a copy of the relevant calibration results required by 40 CFR part 1065.