1999-2001 RX 300 6Cyl. 2WD "DTC" P1135

 P1135  A/F Sensor Heater Circuit Malfunction (BANK 1 - SENSOR 1).

 To obtain a high purification rate of the CO, HC, and NOX components of the exhaust gas, a three way catalytic converter is used, but for the most efficient use of the three catalytic converter, Air – Fuel ratio must be precisely controlled so that it is always close to the stoichiometric Air-Fuel ratio (A/F Sensor). The A/F sensor output voltage is used to provide feedback for the ECM to control the Air-Fuel Ratio.


Replace the A/F SENSOR not the Oxygen sensor (See image). After the sensor is replaced, clear the "DTC" code, and drive about 50 to 60 miles to make sure that sensor is working properly.

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