Mechanics

O2 SENSOR HEATER CIRCUIT MALFUNCTION (BANK 2, SENSOR 2)

Ford Contour

I have a 1999 Ford Contour, 2.5 DOHC and the engine light came on. I have an OBD II Code reader and I have code P0161. I know it has to do with the O2 Senson but which one? It says Bank 2, Sensor 2 in the definition of the code. Do I replace the one in the front or back?

Thanks!
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SFC K
September 6, 2007.




Bank 2 sensor 2 will in a six or eight cyl engine the oposite pipe from cly 1, that would be bank 1 sensors 1, wich is before converter, and sensor 2, after the converter

Merlin2021
Sep 6, 2007.
So is there three O2 Senseons on this engine then? I know that there is one in the front manifold and one in the rear which means they are before the CAT, so I need the one after the CAT?

Tiny
SFC K
Sep 6, 2007.
So is there three O2 Senseons on this engine then? I know that there is one in the front manifold and one in the rear which means they are before the CAT, so I need the one after the CAT?[/Quote: dbced05018]
I'm a little confused; Ok after reading this over and looking through the manual I need to replace the one located in the rear Exhaust manifold closest to the fire wall next to cly's 1, 2, and 3, right? This would be after the converter right?
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Tiny
SFC K
Sep 6, 2007.
I think you need to count the converters, if you have only 1 in a y pipe ypu will have 3 sensors, change the one after the cat, if you have dual exhuast and 2 converters you'll have 4 sensors.

Merlin2021
Sep 6, 2007.
Ok, I have one converter and no dual exhaust. I looked at the underneath of the car and on the manifold that is in front there is two sensors. One is at the top of the manifold and one is located lower after a bulge in the pipe just before it connects to another pipe that runs back to the Y pipe. I see only one sense on the rear manifold that I can see. What is confusing to me is that the catalytic converter is after all of this and that is why im confused as to which one it is.

Tiny
SFC K
Sep 6, 2007.
Change the one in back.

Merlin2021
Sep 6, 2007.
I'm sorry I made it hard then it was. I will do just that. You do see why I was confused though.

Thanks for your help!

Tiny
SFC K
Sep 6, 2007.
Where is it if you have Dual Exhaust.

Tiny
Oper026
Feb 13, 2010.
4 cylinder engines normally have 2 sensors, 1 before the cat and one either in the cat or behind the cat, sensor 1 I is before, sensor 2 is after. 6 an eight cylinder engines have three on a y pipe exhaust system, and four on an H pipe exhaust system. Sensor 2 is ALWAYS AFTER the cat. The banks are the confusing part, and it is by maker of the car, but if you look at your valve covers, one is slightly forward of the other one, and is bank one. Bank one's first spark plug is at cylinder one!

Merlin2021
Feb 13, 2010.
Why not state that up front and not just side step the question. I apologize I confused bank 2 with sensor 2 will you be able to answer why the O2 sensor after the cat is at a constant 1.25 reguardless if the temperature of the car. Is it safe to say the Sensor is bad?

Tiny
Bcmullen95
May 20, 2011.

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