Document ID: chunk:federal_register_of_legislation:F2023L00129:reg:99:p27
Version: federal_register_of_legislation:F2023L00129
Segment Type: reg
Provision Reference: reg 99 (pt 27/39)
Character Range: 1229850–1232780

begin counting as soon as a malfunctioning gas supply is detected according to paragraph 7.2 of this annex and the corresponding diagnostic trouble code (DTC) has the status confirmed and active.

              A.2.1.2.1.2.  The counter shall halt and hold its current value if a single monitoring event occurs and the malfunction that originally activated the counter is no longer detected or if the failure has been erased by a scan tool or a maintenance tool.

              A.2.1.2.1.2.1.  The counter shall also halt and hold its current value when the service mode becomes active.

              A.2.1.2.1.3.  Once frozen, the counter shall be reset to zero and restart counting if a malfunction relevant to that counter is detected and the service mode activated.

              A.2.1.2.1.3.1.  Once frozen, the counter shall also be reset to zero when the monitors relevant to that counter have run at least once to completion of their monitoring cycle without having detected a malfunction and no malfunction relevant to that counter has been detected during 36 engine operating hours since the counter was last held.

       A.2.1.3. Illustration of the counter mechanism

              Figures A2.1.1 to A2.1.3 give via three use-cases an illustration of the counter mechanism

Figure A2.1.1
Illustration of the gas supply counter mechanism (Type A HDDF) - use-case 1
A malfunction of the gas supply is detected for the very first time.
       The service mode is activated and the counter starts counting once the DTC gets the "confirmed and active" status (2nd detection).

       The vehicle encounters a stand-still situation before reaching 30 minutes operating time after the service mode is activated.

       The service mode becomes active and the vehicle speed is limited to 20 km/h (see paragraph 4.2.2.1. of this annex).

       The counter freezes at its present value.

       A malfunction of the gas supply is detected while the gas supply malfunction counter is not at zero (in this use-case it indicates the value it reached in use-case 1 when the vehicle became standstill).

       The service mode is activated and the counter restarts counting from zero as soon as the DTC gets the "potential" status (1st detection: see paragraph 4.2.3.2.1. of this annex).

       After 30 minutes of operation without a standstill situation, the service mode becomes active and the vehicle speed is limited to 20 km/h (see paragraph 4.2.2.1 of this annex).

       The counter freezes at a value of 30 minutes operating time.

       After 36 operating hours without detection of a malfunction of the gas supply, the counter is reset to zero (see paragraph A.2.1.2.3.2.1).

       A malfunction of the gas supply is again detected while the gas supply malfunction counter is at zero (1st detection).

       The service mode is activated and the counter starts counting once the DTC gets the "confirmed and