Component Tests and General Diagnostics

HEATED OXYGEN SENSOR (HO2S) INSPECTION

HO2S Voltage Inspection

NOTE: Perform the following test only when directed.

1. Warm up the engine and run it at idle.
2. Disconnect the HO2S (front or rear) connector.
3. Connect the voltmeter test leads to the following HO2S terminals:
- HO2S (Front, RH) and HO2S (Rear, RH)
- (+) lead-terminal A
- (-) lead-terminal B
- HO2S (Front, LH) and HO2S (Rear, LH)
- (+) lead-terminal A
- (-) lead-terminal B

4. Run the engine at 3,000 rpm until the voltmeter moves between approx. 0 and 1.0 V.

5. Verify that the measurement voltage changes when the engine speed increases and decreases suddenly several times.
- If not as specified, replace the HO2S.
- If the HO2S is okay, but PID value or PCM terminal voltages are out of specification, perform the "Circuit Open/Short Inspection".

HO2S Circuit Open/Short Inspection

1. Disconnect the PCM connector.(See PCM REMOVAL/INSTALLATION.)

2. Connect the SST (104 Pin Breakout Box) with the PCM disconnected.
3. Tighten the connector attaching bolt.

Tightening torque: 3.0-5.4 Nm {30-56 kgf.cm, 27-48 in.lbf}

4. Inspect the following wiring harness for open or short circuit (Continuity check).

Open circuit
- If there is no continuity, the circuit is open. Repair or replace the harness.
- HO2S (Front, RH) terminal A (harness-side) and 104 pin breakout box terminal 60
- HO2S (Front, RH) terminal B (harness-side) and 104 pin breakout box terminal 91
- HO2S (Rear, RH) terminal A (harness-side) and 104 pin breakout box terminal 35
- HO2S (Rear, RH) terminal B (harness-side) and 104 pin breakout box terminal 91
- HO2S (Front, LH) terminal A (harness-side) and 104 pin breakout box terminal 87
- HO2S (Front, LH) terminal B (harness-side) and 104 pin breakout box terminal 91
- HO2S (Rear, LH) terminal A (harness-side) and 104 pin breakout box terminal 61
- HO2S (Rear, LH) terminal B (harness-side) and 104 pin breakout box terminal 91

Short circuit
- If there is continuity, the circuit is shorted.Repair or replace the harness.
- HO2S (Front, RH) terminal A (harness-side) and body ground
- HO2S (Front, RH) terminal A (harness-side) and power supply
- HO2S (Front, RH) terminal B (harness-side) and power supply
- HO2S (Rear, RH) terminal A (harness-side) and body ground
- HO2S (Rear, RH) terminal A (harness-side) and power supply
- HO2S (Rear, RH) terminal B (harness-side) and power supply
- HO2S (Front, LH) terminal A (harness-side) and body ground
- HO2S (Front, LH) terminal A (harness-side) and power supply
- HO2S (Front, LH) terminal B (harness-side) and power supply
- HO2S (Rear, LH) terminal A (harness-side) and body ground
- HO2S (Rear, LH) terminal A (harness-side) and power supply
- HO2S (Rear, LH) terminal B (harness-side) and power supply

HO2S Heater Resistance Inspection
1. Disconnect the HO2S (front or rear) connector.
2. Measure the resistance between the following HO2S terminals.
- HO2S (Front, RH) and HO2S (Rear, RH)
- Terminal C and D
- HO2S (Front, LH) and HO2S (Rear, LH)
- Terminal C and D
- If not as specified, replace the HO2S.
- If the HO2S heater is okay, but PID value or any of PCM terminal 94, 93, 95, 96 voltage are out of specification, perform the "Circuit Open/Short Inspection".

Specification
Front (RH, LH): 5.0-6.8 ohms
Rear (RH, LH): 14.1-18.9 ohms

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

2. Connect the SST (104 Pin Breakout Box) with the PCM disconnected.
3. Tighten the connector attaching bolt.

Tightening torque: 3.0-5.4 Nm {30-56 kgf.cm, 27-48 in.lbf}