The oxygen sensor heater element has an internal resistor that heats up when current flows through it to warm up the oxygen sensor rapidly. The pcm monitors the sensor circuit and would set trouble codes if it detects an electrical fault within the circuit.

In this video,I analyze the heater circuit wiring diagram, and I run multiple tests using a multimeter and an oscilloscope testing the control side of the circuit to check PCM operation.

TIMELINE:
0:00 Intro
0:14 Wiring diagram analysis
2:30 Locating oxygen sensor connector
3:10 Identifying sensor connector view
4:00 Heater circuit ID
4:07 Heater resistance test
5:10 Resistance specifications
5:50 Checking heater circuit positive side
6:55 Checking heater circuit negative side
7:33 Testing the heater circuit control side
8:55 Backprobing the heater connector
10:08 Heater circuit description
10:52 Scope and meter testing
12:09 Waveform reference
12:43 KOEO heater circuit
15:12 Simulating a heater circuit problem
16:00 Possible circuit faults
19:50 Bench testing the sensor heater
24:12 Thermal image heater test

Disclaimer:
The content of this video is available for informational and educational purposes only.
I cannot guarantee against improper use or unauthorized modifications of this information. MR. DIAGNOSTECH assumes no liability for property damage or injury incurred as a result of any of the information contained in this video. Use this information at your own risk. Any injury, damage, or loss that may result from improper use of these tools, equipment, or from the information contained in this video is the sole responsibility of the user and not MR. DIAGNOSTECH.