Effect of Bad O Sensor?

[Cburg]

Hi Forum,
What is the effect of a bad oxygen sensor? Does it make for a leaner, or richer fuel/air mix?
Thanks!
Mike

[GasSavers_Erik]

The engine will run richer than it should as the oxygen sensor fails. The sensor will also respond more slowly to changes in the mixture.

When ECU recognizes that the sensor is not working properly, the check engine light will come on and the computer will ignore the oxygen sensor and use a programmed set of values that also cause the engine to run a little rich.

[Cburg]

Thanks Eric!
Mike