Front 02 sensor

[jrvp20]

On my 08 facelift bl5 legacy the o2 sensor was not giving a reading was stuck on 14.70 however the car was fueling fine. Got around 500km on a tank. I changed the o2 sensor a used sensor tho. However now the car burning gas alot and this morning the car is stuttering when pulling off. I disconnected the sensor and its driving normal however the check light is on. I dont have the funds to purchase a new sensor atm. Would it be okay to drive the car?

[relative4]

Sure, if you want to destroy your catalytic  converter.

Put the old sensor back on and do some more diagnosis before throwing parts.

[jrvp20]

What else may cause the front O2 not to read if the sensor itself not bad? I was going to buy a new sensor and install it

Edited August 29, 2023 by jrvp20

[relative4]

1.  What symptoms started you down this road?  Particularly given you say it was fueling fine?

2. How did you determine the sensor is not reading?  The O2 sensor does not read 14.7; that's a calculated A/F ratio that may be highly suspect depending on what's giving you that result.  An O2 sensor gives a cycling voltage.  Did you graph the O2 sensor output?

[jrvp20]

When the car went to tune the tuner said the o2 sensor not giving a reading. Its stuck on 14.70 . He recommended to change it. The car was giving no symptoms of a issue. Thats why i thinking just to put back the old sensor.

[relative4]

Well then, gonna need a lot more info.  Mods, logs, etc.

[m sprank]

Maybe you have a bad heater circuit on the O2 that reads 14.7.  Then maybe the used replacement is actually working and now your car is not running properly because it needs a tune.  You need data to know.

Edited August 30, 2023 by m sprank