Function Explanation (DTC Detection Outline)

The PCM performs verification as to whether a condition in which A/F (air/fuel ratio) detection is not implemented due to poor A/F sensor activation by a decrease in A/F sensor performance or other malfunction has occurred. A DTC is stored if the A/F sensor cannot implement feedback (non-active condition (resistance value is specified value or more)) for a continuous 35 s or more under the condition in which the A/F sensor heater control has been normally implemented. However, under a condition prior to the A/F sensor performing activation (such as ignition switched off), and if there is an open/short circuit (P2251:00) between the A/F sensor terminal D and PCM terminal 1S (COM terminal), or an open/short circuit (P2243:00) between A/F sensor terminal F and PCM terminal 1T (B+ terminal), A/F sensor activation determination is not performed and A/F sensor non-activation (P0134:00) is determined. In addition, if a temporary malfunction is determined in the previous drive cycle because poor A/F sensor activation was determined at the second drive cycle, DTCs are established for each malfunction determination even if the PCM determined a COM open circuit (P2251:00 temporary malfunction) or a B+ open circuit (P2243:00 temporary malfunction) in the previous drive cycle.

Courtesy of MAZDA MOTORS CORP.