| CAUTION | If ECM replacement is instructed in following tests, always ensure ECM connectors and ground circuits are okay. If either are defective, repair and repeat testing to confirm ECM malfunction. |
Note. Heated oxygen sensor No. 2 is located on exhaust pipe in behind catalytic converter and may be referred to as bank No. 1 sensor No. 2.
Note. For component location, see appropriate illustration in THEORY & OPERATION article.
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. DTC is set when heated oxygen sensor No. 2 heater current draw exceeds 2 amps, or heated oxygen sensor heater current draw is .2 amp or less when heater operates. If DTC P0141 exists, ECM will turn off the heater on heated oxygen sensor No. 2. Possible causes are
- Heated oxygen sensor No. 2 heater circuit is open or shorted.
- Defective heated oxygen sensor No. 2 heater.
- Defective ECM.
Diagnostic Aids
Using Toyota hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.