Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Heated Oxygen Sensor -G39-, CHECKING
Observe all safety precautions: SAFETY PRECAUTIONS
View clean working conditions: CLEAN WORKING CONDITIONS
Use only gold-plated terminals when servicing any component with gold-plated electrical harness connector terminals.
For wiring diagrams, component locations, and connector views, Refer to the applicable wiring diagram.
When servicing terminals in harness connector of Heated Oxygen Sensor (HO2S) -G39- / Oxygen Sensor Heater -Z19-, use only gold-plated terminals.
Special tools and workshop equipment required
- Multimeter
- Wiring diagram
Test requirements
- Fuse 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.
Test procedure
-- Perform a preliminary check to verify the customers complaint. Refer to PRELIMINARY CHECK .
Start diagnosis
Checking heater resistance
-- Disconnect the Heated Oxygen Sensor (HO2S) -G39- / Oxygen Sensor Heater -Z19- electrical harness connector -1-.
-- Using a multimeter, measure the resistance of the heater from terminal 3 to terminal 4 of the Heated Oxygen Sensor (HO2S) -G39- / Oxygen Sensor Heater -Z19- connector.
Specified value: 2 - 4 Ω with the exhaust system at room temperature
If the specified value was Not obtained:
-- Replace the Heated Oxygen Sensor (HO2S) -G39- / Oxygen Sensor Heater -Z19-.
If the specified value was obtained:
-- Switch ignition on.
-- Using a multimeter, measure the voltage from terminal 4 of the Heated Oxygen Sensor (HO2S) -G39- / Oxygen Sensor Heater -Z19- harness connector to ground.
Specification: About Battery voltage
-- Switch ignition off.
If specified value is Not obtained:
-- Check for an open, short to ground or high resistance between terminal 4 of the Heated Oxygen Sensor (HO2S) -G39- / Oxygen Sensor Heater -Z19- and the Heated Oxygen Sensor (HO2S) Fuse, (Refer to applicable wiring diagram for fuse positions).
-- If necessary, repair the wiring connection.
If thbe specified value was obtained:
-- Connect scan tool.
-- Start the engine and let idle.
-- Perform the function test located in diagnostic mode 06. Refer to DIAGNOSTIC MODE 06 - READ TEST RESULTS FOR SPECIFIC DIAGNOSTIC FUNCTIONS .
If specified values are 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 values are not obtained:
-- Using a Multimeter, check the Heated Oxygen Sensor (HO2S) -G39- / Oxygen Sensor Heater -Z19- electrical harness connector terminals 2 to 6 for voltage.
Specified value: 0.40 to 2.00 Volts approx.
-- Switch the ignition Off.
If the specified value was obtained:
-- Replace Heated Oxygen Sensor (HO2S) -G39- / Oxygen Sensor Heater -Z19-.
If the specified value was not obtained:
Checking wiring
-- Remove the Heated Oxygen Sensor (HO2S) -G39- / Oxygen Sensor Heater -Z19-.
-- Using a multimeter, check the Heated Oxygen Sensor (HO2S) -G39- / Oxygen Sensor Heater -Z19- electrical harness connector terminals to the Engine Control Module (ECM) -J623- electrical connector T94 for an open circuit.
| Heated Oxygen Sensor (HO2S) -G39- / Oxygen Sensor Heater -Z19- electrical harness connector terminal | Engine Control Module (ECM) -J623- electrical connector T94 terminal |
|---|---|
| 1 | 77 |
| 2 | 56 |
| 3 | 73 |
| 5 | 55 |
| 6 | 78 |
Specified resistance 1.5 Ω max.
If the specification is Not obtained:
-- Check the wiring for high resistance, an open or short circuit to Battery or ground.
-- If necessary, repair the wiring or connection.
If the specification is obtained:
-- Replace the Engine Control Module (ECM) -J623-.
Final procedures
After the repair work, the following work steps must be performed in the following sequence:
- Check the DTC memory. Refer to DIAGNOSTIC MODE 03 - READ DTC MEMORY .
- If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
- If the DTC memory was erased, generate readiness code. Refer to READINESS CODE .
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.