O2 Sensor

[dadejak]

Can a O2 sensor be bad with out having a SES light on?

[bassadict69]

Yes it can... I had a major drop in gas mileage & it was suggested I change the front O2 sensors. I replaced them & mileage came back up...I never got a SES light on mine!

[Draenor]

As James mentioned, yes. I had the same thing. But I am cheap on my car, and just hosed the O2s down with CRC brake and electric connection cleaner. :crosses fingers:

[GMTRUCKTECH]

To set a ses light the parameters have to be right, but also they can be sluggish but not sluggish enough to throw the light so I would change at 100grand. Gas mileage should improve