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DTC P0136: HEATED OXYGEN SENSOR CIRCUIT FAULT Lexus RX I

Note. Bank No. 1 refers to bank which includes cylinder No. 1. Heated oxygen sensor No. 2 refers to sensor furthest away from engine block.

Circuit Description

Heated oxygen sensor monitors exhaust gas oxygen content and delivers an input signal to ECM. ECM uses input signal to determine fuel injection system operation. Heated oxygen sensors include a heater. DTC is set when bank No. 1, sensor No. 2 voltage remains at .4 volt or more, or .6 volt or less during vehicle operation (31 MPH or more), once engine is at normal operating temperature. Possible cause is

  1. Faulty heated oxygen sensor No. 2.

Diagnostic Aids

Using scan tool, read freeze frame data. Freeze frame records engine conditions when malfunction is detected.