Reading Lean? Bad O2?

[andrewjscott]

My blinky light show AFR guage reads lean while warming up, worked fine for about 5 minutes at temperature (oscillating between rich and lean) then it starts to only oscillate between lean and stoich....then only in the lean range, until it always reads lean, and doesn't oscillate. Is this the sign of a bad o2 sensor?

 

[Talesin]

No, it's a sign that you bought a useless lightshow gauge. Hook up your datalogger and get the raw O2 voltage... and if it's still oscillating, the crappy narrowband O2 sensor should still be good (or so says my mechanic). But you'll need to log it to see after it's warmed up.

 

[oldman]

My blinky light show AFR guage reads lean while warming up, worked fine for about 5 minutes at temperature (oscillating between rich and lean) then it starts to only oscillate between lean and stoich....then only in the lean range, until it always reads lean, and doesn't oscillate. Is this the sign of a bad o2 sensor?

Your car doesn't get into close loop until coolant temperature reaches 180ish (not sure what the exact number is).