Component Tests and General Diagnostics
HEATED OXYGEN SENSOR (HO2S) INSPECTIONNOTE: Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flowchart.
HO2S Voltage inspection
1. Warm up the engine to normal operating temperature.
2. Using the WDS or equivalent, monitor the following:
- Vehicle speed (PID: VSS)
- Engine speed (PID: RPM)
- Front/rear HO2S voltage (PID: O2S11/O2S12)
3. Drive the vehicle and decelerate the engine speed by releasing the accelerator pedal fully when the engine speed is 3,000 rpm or more.
4. Verify that the front/rear HO2Soutputs a voltage of 0.6 V or more, one time or more, then verify that the front/rear HO2S voltage (PID: O2S11/O2S12) is 0.3 V or less while decelerating as shown in the figure.
- If not within the specification, inspect the HO2S for an open or short circuit. (See HO2S Voltage inspection.) Then if there is no malfunction in the wiring harness, replace the HO2S.
HO2S Circuit Open/Short Inspection (Sensor)
Open circuit
- If there is no continuity, the circuit is open. Repair or replace the harness.
- Heated oxygen circuit (HO2Sconnector terminal A and PCM connector terminal 4W (Front).)
- GND circuit (HO2Sconnector terminal B and PCM connector terminal 4O through common connector (Front).)
- Heated oxygen circuit (HO2Sconnector terminal A and PCM connector terminal 4AA (Rear).)
- GND circuit (HO2Sconnector terminal B and PCM connector terminal 4O through common connector (Rear).)
Short circuit
- If there is continuity, the circuit is shorted. Repair or replace the harness.
- HO2S connector terminal A and PCM connector terminal 4W to GND (Front).
- HO2S connector terminal A and PCM connector terminal 4AA to GND (Rear).
HO2S Heater Resistance Inspection
NOTE: Perform the following test only when directed.
1. Disconnect the HO2Sconnector.
2. Measure the resistance between HO2S terminals C and D using an ohmmeter.
- If not as specified, replace the HO2S.
- If HO2S heater is okay, but PID value is out of specification, perform the "Circuit Open/Short Inspection".
HO2S heater resistance
Front: 2 - 20 ohms
Rear: 2 - 50 ohms
3. Reconnect the HO2S connector.
HO2S Circuit Open/Short Inspection (Heater)
Open Circuit
- If there is no continuity, the circuit is open. Repair or replace the harness.
- GND circuit (HO2S connector D and PCM connector terminal 3J through common connector (Front).)
- Power circuit (HO2S connector terminal C and ignition switch (IG1) circuit through common connector (Front).)
- GND circuit (HO2S connector terminal D and PCM connector terminal 3P (Rear).)
- Power circuit (HO2S connector terminal C and ignition switch (IG1) circuit through common connector (Rear).)
Short circuit
- If there is continuity, the circuit is shorted. Repair or replace the harness.
- HO2S connector terminal C and ignition switch (IG1) through common connector to GND (Front).
- HO2S connector terminal D and PCM connector terminal 3J through common connector to GND (Front).
- HO2S connector terminal D and PCM connector terminal 3P to GND (Rear).