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 2 - G108- CHECKING
Function
The Heated Oxygen Sensor 2 -G108-, and Oxygen Sensor 2 Heater -Z28- does not actually measure oxygen concentration, but rather the difference between the amount of oxygen in the exhaust gas and the amount of oxygen in the air. Rich mixture causes an oxygen demand. This demand causes a voltage to build up, due to transportation of oxygen ions through the Heated Oxygen Sensor 2 -G108- layer. Lean mixture causes low voltage, since there is an oxygen excess. The Heated Oxygen Sensor 2 -G108- and catalytic converters are used in order to reduce exhaust emissions. Information on oxygen concentration is sent to the Engine Control Module -J623-, which adjusts the amount of fuel injected into the engine to compensate for excess air or excess fuel. The Engine Control Module -J623- attempts to maintain, on average, a certain air-fuel ratio by interpreting the information it gains from the Heated Oxygen Sensor 2 -G108-. The primary goal is a compromise between power, fuel economy, and emissions. The Heater for Heated Oxygen Sensor 2 -G108- is designed to minimize the time-to-readiness for closed-loop operation by heating the Oxygen Sensor 2 Heater -Z28- as quickly as possible.
The Heated Oxygen Sensor 2 -G108- contains the following components:
- Oxygen Sensor 2 Heater -Z28-
The Heated Oxygen Sensor 2 -G108- components cannot be serviced separately, it must be serviced as a unit.
Special tools and workshop equipment required
- Multimeter
- Wiring Diagram
- Scan Tool
Test requirements
- Fuses OK.
- Battery voltage OK.
- Switch OFF all electrical and electronic accessories.
- Vehicles with Auto. Transmission, ensure Selector Lever position is in "P".
- Vehicles with Man. Transmission, ensure Shifter Lever position is in "N" with Parking Brake applied.
- Coolant Temperature: ≥ 80° C.
- Observe all safety precautions: SAFETY PRECAUTIONS .
- View clean working conditions: CLEAN WORKING CONDITIONS .
Test Procedure
| Step | Procedure | Result / Action to Take |
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-- YES:
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| 2 |
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-- YES:
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| 3 |
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-- YES:
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| 4 |
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| 5 |
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-- YES:
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| 6 |
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| 7 |
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-- YES:
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| 8 |
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-- YES:
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| 9 |
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-- YES:
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NO RELATED
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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.