When you filmed this was the engine at full operating temperature? The ECU/fuelling will be in open loop until the coolant is at least 60C.

The readings should be a wave form something like this (averaging out around the 0.45V mark) in closed loop at idle, but only if the O2 sensor is hot enough:



If the trace is flat, that shows that there are no fuelling adjustments taking place or being made by the ECU as a result of sensor input. When the engine is started from cold it will be flat, but should flip high/low voltage 3-4 times a second at idle once warm.

Obviously if you open the throttle it will also switch to open loop and the ECU will ignore the O2 sensor.

As I said before, if both sensors you have tried do the same, then could be a wiring issue somewhere, or the heater element isn't working. Try connecting up to the two heater element wires. You should see a 0-5V square wave if the circuit is working correctly.

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