Need help with a P0155 Code please. Replaced O2 sensor and still getting the code.

[contourguy99]

Hi, Can anyone confirm where Bank 2, Sensor 1 is located on the 1999 Contour SE 2.5L V6 VIN L?
The reason I asked is that I had a P0155 error, and I am still throwing the code after resetting the ECU a few times.

Also does anyone have a test procedure for the sensor and what all triggers this code. No other codes are currently showing or pending. Thanks.

 

[SICILIANSVT82]

Thats an upstream sensor (square harness) thats throwing that code. You can test the sensor by connecting a volt meter to both black wires to see if it had any voltage. Resetting the computer will only turn your CEL off until you drive the car into another drive cycle and then it will illuminate again. You need to replace the sensor( firewall sensor) its the hardest sensor to replace and its right below the coil pack. Just follow it down with your hand, you will find it.

 

[contourguy99]

Thats an upstream sensor (square harness) thats throwing that code. You can test the sensor by connecting a volt meter to both black wires to see if it had any voltage. Resetting the computer will only turn your CEL off until you drive the car into another drive cycle and then it will illuminate again. You need to replace the sensor( firewall sensor) its the hardest sensor to replace and its right below the coil pack. Just follow it down with your hand, you will find it.

I replaced the Sensor, The connector is round on this year model, and the ones without a fuel return line on the fuel pump. Getting a 0v sine wave still. I also cleaned the socket with contact cleaner and let it dry while the car was off no difference. What else could it be? What colors of wires are heater, ground, and signal. What is the proper test procedure for sensor side vs ECM side of the connector too if anyone knows.