DTC 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.