Circuit Description

Refer to DTC P2195 OXYGEN (A/F) SENSOR SIGNAL STUCK LEAN (BANK 1 SENSOR 1),DTC P2196 OXYGEN (A/F) SENSOR SIGNAL STUCK RICH (BANK 1 SENSOR 1) .

HINT:

• When any of these DTCs are set, the ECM enters fail-safe mode. The ECM turns off the A/F sensor heater in fail-safe mode. Fail-safe mode continues until the ignition switch is turned to OFF.
• The ECM provides a pulse width modulated control circuit to adjust the current through the heater. The A/F sensor heater circuit uses a relay on the +B side of the circuit.

Fig 1: Oxygen Sensor Heater Control Circuit Reference Diagram (Sensor 1)

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

Fig 2: DTC Trouble Detection Chart (DTC P0031/0032)

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.