DTC P2099: General Description
The powertrain control module (PCM) detects oxygen content in the exhaust gas by the front air/fuel ratio (A/F) sensor (bank 2, sensor 1), and it uses feedback control before the front warm up three way catalytic converter (WU-TWC) (bank 2) to bring the air/fuel ratio close to the target air/fuel ratio. The target air/fuel ratio is adjusted by the front secondary heated oxygen sensor (secondary HO2S (bank 2, sensor 2)) output so that the air/fuel ratio in the front WU-TWC (bank 2) is optimized. When the front A/F sensor (bank 2, sensor 1) cannot measure air/fuel ratio in the exhaust gas normally, a gap occurs to the actual air/fuel ratio. As a result, the gap causes a deviation in target air/fuel ratio control (after front WU-TWC (bank 2)) which is determined by the front secondary HO2S (bank 2, sensor 2). If the deviation exceeds a limit, the PCM detects a malfunction and stores a DTC.