§ 1042.110 Recording reductant use and other diagnostic functions.
(a) Engines equipped with SCR systems using a reductant other than the engine's fuel must meet the following requirements:
(1) The diagnostic system must monitor reductant supply and alert operators to the need to restore the reductant supply, or to replace the reductant if it does not meet your concentration specifications. Unless we approve other alerts, use a warning lamp and an audible alarm. You do not need to separately monitor reductant quality if your system uses input from an exhaust NOX sensor (or other sensor) to alert operators when reductant quality is inadequate. However, tank level or DEF flow must be monitored in all cases.
(2) The onboard computer log must record in nonvolatile computer memory all incidents of engine operation with inadequate reductant injection or reductant quality. Use good engineering judgment to ensure that the operator can readily access the information to submit the report required by § 1042.660. For example, you may meet this requirement by documenting the incident in a text file that can be downloaded or printed by the operator.