Heated Oxygen Sensor, Checking

Special tools and workshop equipment required 

• Multimeter.
• Wiring diagram.

Test requirements 

• The Fuses OK.
• The Oxygen Sensor (O2S) Heater -G39- before catalytic converter OK.
• Battery voltage at least 12.5 volts.
• All electrical consumers such as, lights and rear window defroster, switched off.
• A/C switched off.
• Ground connections between engine/transmission/chassis OK.
• Exhaust system between catalytic converter and cylinder head properly sealed.
• Coolant Temperature at least 80 °C.

Test procedure 

-- Perform a preliminary check to verify the customers complaint. Refer to PRELIMINARY CHECK 

Start diagnosis 

-- Connect scan tool.

-- Start the engine and let it run at idle.

-- Select "Diagnostic mode 6: Check test results of components that are not continuously monitored".

-- Select Monitor-ID $01: Oxygen sensor monitoring before catalytic converter.

-- Check the values at idle and compare to the Monitor-ID $01 tables. Refer to DIAGNOSTIC MODE 06 - READ TEST RESULTS FOR SPECIFIC DIAGNOSTIC FUNCTIONS => Monitor-ID $01: Oxygen Sensor Monitor Bank 1 - Sensor 1 .

-- Switch the Ignition Off.

If the specified value was obtained: 

-- Fault may be intermittent.

-- Check for loose or corroded connections and any leaks in the exhaust.

-- Check Freeze Frame data for conditions when the DTC set.

-- Go to Final procedures

If the specified value was Not obtained: 

Checking voltages 

-- Switch the Ignition On.

-- Using a Multimeter, check the Heated Oxygen Sensor (HO2S) -G39- electrical harness connector terminals 2 to 6 for voltage.

Specified value: 0.400 to 0.500 Volts

-- Switch the ignition Off.

If the specified value was obtained: 

-- Replace Heated Oxygen Sensor (HO2S) -G39-.

If the specified value was not obtained: 

Checking wiring 

-- Remove the Engine Control Module (ECM) -J623-.

-- Using a Multimeter, check the Heated Oxygen Sensor (HO2S) -G39- electrical harness connector terminals to the Engine Control Module (ECM) -J623- electrical harness connector T94 terminals for an open circuit.

Heated Oxygen Sensor (HO2S) -G39- electrical harness connector terminals	Engine Control Module (ECM) -J623- electrical connector T94 terminals.
1	78
2	79
5	56
6	57

Specified value: 1.5 Ω Max.

If the specification was not obtained: 

-- Check the wiring for a short circuit to each other, Battery Voltage, and Ground (GND).

-- Check the electrical harness connector for damage, corrosion, lose or broken terminals.

-- If necessary, repair the faulty wiring connection.

If the specification was obtained: 

-- Replace the Engine Control Module (ECM) -J623-.

Final procedures 

-- Assembly is performed in the reverse order of removal.

After the repair work, the following work steps must be performed in the following sequence: 

1. Check the DTC memory. Refer to DIAGNOSTIC MODE 03 - READ DTC MEMORY .
2. If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
3. If the DTC memory was erased, generate readiness code. Refer to READINESS CODE .