O2 Sensor question.

[Mr Sparkle]

Anyone know about O2 sensors? Have a misfire and wondered if it could be bad.

Anyway with a warm engine, at idle what voltage might one expect to see. ie. a continuous high (0.8v), continuous low (0.1v) or a continuous fluctuation in value? The reason is I have two sensors and one gives continuous high and the other fluctuates but don’t know which one is correct. Think engine is running rich.

[buggalugs]

Fluctuation is normal, just over once per second at a fast idle IIRC.

[Nick1point9]

'Switching' is correct. For a non wide band lambda sensor you should expect the sensor to read high, take corrective action until it reads low, take corrective action until it reads high and so on.

[Mr Sparkle]

Thanks guys.

[maniac0796]

An older sensor should fluctuate between 0.2 and 0.8v when on closed loop, and a wide band should be between roughly 0.5 to 5v.

You might have a heater wire at battery voltage as well.