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DTC codes / P2Axx · Hybrid propulsion / P2A3B
P2A3B indicates that the engine control module has detected an open circuit or abnormal negative current flow in the control circuit for the downstream oxygen sensor on bank 1, sensor 3. This sensor monitors oxygen storage efficiency after the catalytic converter, and the fault prevents the module from accurately controlling the sensor's heater or signal return path.
Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.
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