P1128 - CLOSED LOOP FUELING NOT ACHIEVED - BANK 1. P1129 - CLOSED LOOP FUELING NOT ACHIEVED - BANK 2. When Monitored: Engine running in closed loop mode. Set Condition: Enable conditions are met and the 02 sensor has not been in closed loop control at least once on each of the two consecutive trips, the MIL illuminates and the DTC is set. More @Wikipedia
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