Document ID: chunk:federal_register_of_legislation:F2023C00229:reg:110:p39
Version: federal_register_of_legislation:F2023C00229
Segment Type: reg
Provision Reference: reg 110 (pt 39/59)
Character Range: 713451–716510

procedures laid down for type-approval and in-service surveys.

         6.        DIAGNOSTIC SIGNALS

             6.1. Upon determination of the first malfunction of any component or system, 'freeze-frame' engine conditions present at the time must be stored in computer memory. Stored engine conditions must include, but are not limited to calculated load value, engine speed, coolant temperature, intake manifold pressure (if available), and the fault code which caused the data to be stored. For freeze-frame storage, the manufacturer must choose the most appropriate set of conditions facilitating effective repairs.

             6.2. Only one frame of data is required. Manufacturers may choose to store additional frames provided that at least the required frame can be read by a generic scan tool meeting the specifications of sections 6.8.3 and 6.8.4. If the fault code causing the conditions to be stored is erased in accor- dance with section 3.9 of this Annex, the stored engine conditions may also be erased.

             6.3. If available, the following signals in addition to the required freeze-frame information must be made available on demand through the serial port on the standardised data link connector, if the information is available to the on-board computer or can be determined using information avail- able to the on-board computer: diagnostic trouble codes, engine coolant temperature, injection timing, intake air temperature, manifold air pres- sure, air flow rate, engine speed, pedal position sensor output value, calculated load value, vehicle speed and fuel pressure.

              The signals must be provided in standard units based on the specifications given in section 6.8. Actual signals must be clearly identified separately from default value or limp-home signals.

             6.4. For all emission control systems for which specific on-board evaluation tests are conducted, separate status codes, or readiness codes, must be stored in computer memory to identify correctly functioning emission control systems and those emission control systems which require further vehicle operation to complete a proper diagnostic evaluation. A readiness code need not be stored for those monitors that can be considered continuously operating monitors. Readiness codes should never be set to 'not ready' status upon 'key-on' or 'key-off'. The intentional setting of readiness codes to 'not ready' status via service procedures must apply to all such codes, rather than applying to individual codes.

             6.5. The OBD requirements to which the vehicle is certified (i.e. stage 1 OBD or stage 2 OBD) and the major emission control systems monitored by the OBD system consistent with section 6.8.4 must be available through the serial data port on the standardised data link connector according to the specifications given in section 6.8.

             6.6. The software calibration identification number as declared in Annexes II and VI to Directive 2005/55/EC shall be made available through the serial port of the