Determine which is bad, o2 sensor or o2 harness, Swap test example: front cylinder afr reading bad, Swap test example: rear cylinder afr reading bad – ThunderMax Oxygen (O2) Sensor Operation Testing User Manual
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Determine which is bad, O2 Sensor or O2 Harness
A basic “Swap and Test” procedure can be used to isolate “which” component is faulty, the O2 Sensor or the O2
Harness.
Determine which cylinder AFR reading, Front or Rear, is bad.
Swap Test Example: FRONT cylinder AFR reading bad.
1. Disconnect the O2 harness connectors from the Front and Rear O2 sensors.
2. Connect the O2 harness connector marked “Front” to the REAR O2 sensor.
3. Connect the O2 harness connector marked “Rear” to the Front O2 sensor.
4. Start the engine and verify AFR readings for both cylinders.
5. If the FRONT AFR reading is “STILL” in error, the O2 Harness is at fault.
6. If the REAR AFR reading is “NOW” in error, the FRONT O2 Sensor is faulty.
7. If the FRONT and REAR AFR readings now are GOOD, a harness, wiring or connector issue exists.
Swap Test Example: REAR cylinder AFR reading bad.
1. Disconnect the O2 harness connectors from the Front and Rear O2 sensors.
2. Connect the O2 harness connector marked “Front” to the REAR O2 sensor.
3. Connect the O2 harness connector marked “Rear” to the Front O2 sensor.
4. Start the engine and verify AFR readings for both cylinders.
5. If the REAR AFR reading is “STILL” in error, the O2 Harness is at fault.
6. If the FRONT AFR reading is “NOW” in error, the REAR O2 Sensor is faulty.
7. If the FRONT and REAR AFR readings now are GOOD, a harness, wiring or connector issue exists.