Job Sheet 10

Name ______Date ______

Inspect, Diagnose, and Repair Zirconia Oxygen Sensor

Upon completion of this job sheet, you should be able to determine zirconia O2 sensor operation using a digital volt-ohmmeter.
ASE Correlation
This job sheet is related to the ASE L1 Advanced Engine Performance Specialist Test’s content area: B. Computerized Powertrain Controls Diagnosis—including OBD II; Task: 1. Inspect and test for missing, modified, inoperative, or tampered computerized powertrain components. Locate relevant service information. Research system operation using technical information to determine diagnostic procedure. Using appropriate diagnostic procedure based on available vehicle data and service information, determine if available information is adequate to proceed with effective diagnosis. Interpret scan tool data to determine system condition. Establish relative importance of displayed scan tool data. Differentiate between computerized powertrain controls problems and mechanical problems. 2. Evaluate scan tool data and confirm accuracy using direct measurement. 3. Determine root cause of failures. Determine root cause of multiple component failures. Determine root cause of repeated component failures.
Tools and Materials
Late-model vehicle
Service manual or information system
Safety glasses or goggles
Hand tools, as required
Digital multimeter
Describe the vehicle being worked on:
Year______Make______Model ______
VIN ______Engine type and size ______
Procedure
Always follow the procedures outlined in the service manual. Give a brief description of your procedure following each step. Ensure that the engine is cold, and wear eye protection before you begin.
1.Use the appropriate service information to locate the wiring diagrams and diagnostic steps for this procedure. The steps listed below are intended to be generic in nature and should not supersede those recommended by the manufacturer. / Task completed

Inspect, Diagnose, and Repair Zirconia Oxygen Sensor (continued)

2.Locate the oxygen sensor[s] and backprobe the sensor signal wire with a T-pin. Attach the red lead of the DVOM to the sensor signal wire and the black lead to a good ground. Start the engine and allow it to run at 2,500 rpm for 2 minutes to get the oxygen sensor to operating temperature and the engine into closed-loop operation. On the DVOM, select the MIN/MAX record function and maintain the engine at 2,500 rpm and record the results in the table below after 2 minutes.
Minimum voltage
Maximum voltage
Average voltage
Sensor OK/NOT OK
/ Task completed

Results: MIN should be below 200 mV and MAX should be above 800 mV. The average should be about 450 mV.
a.If the average is higher than 450 mV, the engine is operating with a rich air-fuel mixture.
b.If the average is lower than 450 mV, the engine is operating with a lean air-fuel mixture.