O2 ?

[Dave Noll]

Originally Posted by Jeff Stout

If a O2 sensor is going bad what will it do? Mine is showing 18 to 21 AFR now and car is fine and runs the same. Last month it was showing 16 to 18 AFR. No header gasket leak that I can hear or see. Plugs read normal and ET is where it should be. The sensor is about 3 years old with C12 and C16 for fuel

C12 is leaded. Leaded gas coats the sensor, it will read a low voltage which is interpreted as lean. When I use an O2 in mine, I only use C10.