Oxygen Sensor 1 Before Catalytic Converter - GX10-, Checking

General Description

The Oxygen Sensor 1 Before Catalytic Converter -GX10- 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 air. Rich mixture causes an oxygen demand. This demand causes a voltage to build up, due to transportation of oxygen ions through the Oxygen Sensor 1 Before Catalytic Converter -GX10- layer. Lean mixture causes low voltage, since there is an oxygen excess. The Oxygen Sensor 1 Before Catalytic Converter -GX10- and catalytic converters are used in order to reduce exhaust emissions. Information on oxygen concentration is sent to 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 Oxygen Sensor 1 Before Catalytic Converter -GX10-. The primary goal is a compromise between power, fuel economy, and emissions. The heater for Oxygen Sensor 1 Before Catalytic Converter -GX10- is designed to minimize the time-to-readiness for closed-loop operation by heating the Oxygen Sensor 1 Before Catalytic Converter -GX10- as quickly as possible.

Note the Oxygen Sensor 1 Before Catalytic Converter -GX10- is also referred to as the Heated Oxygen Sensor -G39-.

The Oxygen Sensor 1 Before Catalytic Converter -GX10- contains the following components:

Oxygen Sensor Heater -Z19-
Heated Oxygen Sensor -G39-

The Oxygen Sensor 1 Before Catalytic Converter -GX10- components cannot be serviced separately, and 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.
Observe all safety precautions: SAFETY PRECAUTIONS .
View clean working conditions: CLEAN WORKING CONDITIONS .

Test Procedure

Step	Procedure	Result / Action to Take
1	PERFORM: Preliminary Check to verify the customers complaint. Refer to Oxygen Sensor Preliminary Tests in PRELIMINARY CHECK . -- Was Complaint verified?	-- YES: GO TO: Step 2. -- NO: GATHER more information from customer about the complaint.
2	IGNITION: OFF. DISCONNECT: Oxygen Sensor 1 Before Catalytic Converter -GX10- harness connector. CHECK: Oxygen Sensor 1 Before Catalytic Converter -GX10- component connector terminals 3 to 4 for resistance. SPECIFIED VALUE: 2 - 4 Ω (@ 25° C). -- Was Value obtained?	-- YES: GO TO: Step 3. -- NO: REPLACE: Oxygen Sensor 1 Before Catalytic Converter -GX10-. Refer to appropriate Service Information. GO TO: Step 6.
3	IGNITION: ON. CHECK: Oxygen Sensor 1 Before Catalytic Converter -GX10- harness connector terminal 4 to ground for voltage. IGNITION: OFF. SPECIFIED VALUE: Battery voltage. -- Was Value obtained?	-- YES: GO TO: Step 4. -- NO: PERFORM: Visual Inspection of wiring and component. CHECK: Wiring for open, high resistance, short or harness connector for damage, corrosion, loose or broken terminals. REPAIR: Faulty wiring or connector. GO TO: Step 6.
4	RECONNECT: Oxygen Sensor 1 Before Catalytic Converter -GX10- harness connector. CONNECT: Scan Tool. START: Engine and let Idle. Perform the function test located in diagnostic mode 06. Refer to appropriate Diagnostic Mode 06 - Read Test Results for Specific Diagnostic Functions, DIAGNOSTIC MODES 01 - 0A . IGNITION: OFF. SPECIFIED VALUE: Mode 6 Pass. -- Were Values obtained?	-- YES: FAULT: Is intermittent. PERFORM: Visual Inspection of wiring and component. CHECK: Wiring for open, high resistance, short or harness connector for damage, corrosion, loose or broken terminals. REPAIR: Faulty wiring or connector. GO TO: Step 6. -- NO: GO TO: Step 5.
5	DISCONNECT: Oxygen Sensor 1 Before Catalytic Converter -GX10- harness connector. REMOVE: Engine Control Module -J623-. Refer to appropriate Service Information. CHECK: Oxygen Sensor 1 Before Catalytic Converter -GX10- harness connector terminal 1 to the Engine Control Module -J623- harness connector T91 / 27 for resistance. CHECK: Oxygen Sensor 1 Before Catalytic Converter -GX10- harness connector terminal 2 to the Engine Control Module -J623- harness connector T91 / 12 for resistance. CHECK: Oxygen Sensor 1 Before Catalytic Converter -GX10- harness connector terminal 3 to the Engine Control Module -J623- harness connector T91 / 91 for resistance. CHECK: Oxygen Sensor 1 Before Catalytic Converter -GX10- harness connector terminal 5 to the Engine Control Module -J623- harness connector T91 / 10 for resistance. SPECIFIED VALUE: 0.5 Ω (± 0.3 Ω). -- Were Values obtained?	-- YES: REPLACE: Oxygen Sensor 1 Before Catalytic Converter -GX10-. Refer to appropriate Service Information. GO TO: Step 6. -- NO: PERFORM: Visual Inspection of wiring and component. CHECK: Wiring for open, high resistance, short or harness connector for damage, corrosion, loose or broken terminals. REPAIR: Faulty wiring or connector. GO TO: Step 6.
6	Final Procedure Perform a road test to verify repair. -- Does the original DTC return?	-- YES: CHECK: Engine Control Module -J623- harness connector for any damaged, pushed-out pins. REPAIR: As necessary. If all electrical connections are OK: REPLACE: Engine Control Module -J623-. Refer to appropriate Service Information. Clear the DTC's. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY . Repair is complete. Generate Readiness Code. Refer to READINESS CODE . Return vehicle to Customer. -- NO: Perform the diagnostic procedure for any DTC's. If no DTC's return the repair is complete. Return vehicle to customer.