O2 weird situation
 

Hello, can someone please help me with a weird situation regarding an o2 sensor that is acting very strange
So, the story is this, about an year ago I bought a 986 from 99. Love the car but i had stored in the ecu an error: o2 ahead of cat bank 1 no signal. No check engine on the dash.
I proceeded to change the sensor with a brand new Bosch part. After installing the part i now get the error: 02 Sensor Ahead Of Cat. Conv., Cylinder (1-3) below limit value
No leaks on the exhaust, the check engine is off but i don t get it why the ecu shows this error, specially the o2 is new.
Could this be related to the fact that i have a Dansk Motorsport exhaust?

Thank you

More likely a wiring harness issue.

Sorry, just edited the first post. The error i got now is 02 Sensor Ahead Of Cat. Conv., Cylinder (1-3) below limit value
To give more details about this situation, when I finished mounting the new sensor, I started the car and I check with my scanner the values of the new o2. The values were great, 0.2 -0,7.
Then after 10 minutes of driving, I checked again and the values are with minus (-0.1 - -0.3).

What code numbers are you seeing?

02 Sensor Ahead Of Cat. Conv., Cylinder (1-3) below limit value, I do not have a code, my scanner shows only this error.

Without the actual codes, I cannot help you any further..................

I think is p0133

P0133 is the aging out of the sensor ahead of the three way cat on bank #1.

Again sorry, today i diagnosed the car with a different scanner. The error code is:
P1115 - Oxygen Sensor heating side 1 ahead of Cat - below lower threshold

Back to JFP’s original comment - sounds like wiring problems.

P1115:

Heating current too low

-Interruption in heater circuit
-Interruption in sensor wires
-Short circuit