| CAUTION | If ECM replacement is instructed in following testing, always ensure ECM harness connectors and ground circuits are okay. If either are defective, repair and repeat testing to confirm ECM malfunction. If ECM is replaced, ECM must be programmed with proper ignition key code for engine immobilizer system. For programming procedures, see COMPUTER RELEARN PROCEDURES - IMPORT article in GENERAL INFORMATION, or appropriate ENGINE IMMOBILIZER SYSTEMS article in ACCESSORIES & EQUIPMENT. |
Circuit Description
Heated oxygen sensor monitors exhaust gas oxygen content and delivers an input signal to ECM. Heated oxygen sensor No. 2 may be referred to as (bank No. 1 sensor No. 2) and is located on exhaust pipe behind catalytic converter. ECM uses input signal to determine fuel injection system operation. Heated oxygen sensors include a heater. DTC is set when heated oxygen sensor heater current draw exceeds 2 amps, or heated oxygen sensor heater current draw is .2 amp or less when heater operates. 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.