DTC P2096, P2097: General Description
The powertrain control module (PCM) detects oxygen content in the exhaust gas by the air/fuel ratio (A/F) sensor (sensor 1), and it uses feedback control before the three way catalytic converter (TWC) to bring the air/fuel ratio close to the target air/fuel ratio. The target air/fuel ratio is adjusted by the secondary heated oxygen sensor (secondary HO2S (sensor 2)) output so that the air/fuel ratio in the TWC is optimized. When the A/F sensor (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 TWC) which is determined by the secondary HO2S (sensor 2). If the deviation exceeds a limit, the PCM detects a malfunction and stores a DTC.