HO2S Voltage Inspection
Note
1. Warm up the engine and run it at idle.
2. Disconnect the HO2S connector.
3. Connect the voltmeter test leads to the following HO2S terminals:
- (+) leadterminal A
- (-) leadterminal B

4. With the vehicle stopped, run the engine at 3,000 rpm
until the voltmeter moves between 0.5 and 0.7 V.
5. Verify that the measurement voltage changes when the engine speed increases and decreases suddenly several times.
Specification

Circuit Open/Short Inspection (Sensor)
1. Disconnect the PCM connector. (See PCM REMOVAL/INSTALLATION.)

2. Inspect the following wiring harnesses for open or short. (Continuity check)
Open circuit
Front
- HO2S terminal A (harness-side) and PCM terminal 1AB (harness-side)
- HO2S terminal B (harness-side) and PCM terminal 2H (harness-side)
Rear
- HO2S terminal A (harness-side) and PCM terminal 1Y (harness-side)
- HO2S terminal B (harness-side) and PCM terminal 2H (harness-side)
Short circuit
Front and Rear
- HO2S terminal A (harness-side) and body GND
- HO2S terminal A (harness-side) and power supply
- HO2S terminal B (harness-side) and power supply
HO2S Heater Resistance Inspection
1. Disconnect the HO2S connector.
2. Measure the resistance between the HO2S terminals C and D.
Specification
Front : 3.0-3.6 ohms
Rear : 5-7 ohms

Circuit Open/Short Inspection (Heater)
1. Disconnect the PCM connector. (See PCM REMOVAL/INSTALLATION.)

2. Inspect the following wiring harnesses for open or short. (Continuity check)
Open circuit
Front
- HO2S terminal C (harness-side) and ignition switch
- HO2S terminal D (harness-side) and PCM terminal 4A (harness-side)
Rear
- HO2S terminal C (harness-side) and ignition switch
- HO2S terminal D (harness-side) and PCM terminal 4D (harness-side)
Short circuit
Front and rear
- HO2S terminal C (harness-side) and body GND
- HO2S terminal D (harness-side) and power supply
- HO2S terminal D (harness-side) and body GND
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