I have a 03 Expedition, 2x4, 4.6l engine w/ 101K miles. It has had a problem with a rough not quite grinding noise when it gets warm. It sounds like it was coming from underneath the drivers seat. I thought it was most likely the exhaust or catalytic converter area. I thought it was a rattle, but Saturday the check engine light came on and it was idling real rough (almost cutting out) and surging. I immediately thought O2 sensor. That is where my knowledge and experience stops. Took it to Autozone, and the following codes came up: P2195, P2197 and P0171. All of these pointed to the O2 sensors. My questions are as follows:

P2192 says "Lack of O2 sensor - Bank 1, Sensor 1"
P2197 says "Lack of O2 sensor - Bank 2, Sensor 1"
In my lack of time I replaced the front "up stream" sensors on the right and left. I still have the surging and rough idle! Where is Bank 1 and Bank 2? I assumed that since they both said sensor 1 I assumed they were the ones before the catalytic converter. Am I correct with O2 sensor?

I was also assuming that the P0171 was related to the bad O2 sensors. I have read that O2 sensor is often misdiagnosed for P0171.

Any direction will be greatly appreciated!

Thanks!

Mike

 

Bank 1 is the passenger side
bank 2 is the driver side
Sensor 1 is the sensor before the converter nearest the engine.

You replaced the correct 2.
Usually the P0171 code is cause by either a vacuum leak (bad pcv hose elbow) or a dirty MAF sensor.

The noise that you hear almost sounds like a cat converter has come apart internally which will often restrict the exhaust.

 

Vacuum leak it was the 90 degree elbow on the back of the manifold was bad. I guess changing the O2 sensors isn't a loss since it has 101K on it.

Thanks for your input!!!!!

Mike

 

Glad you got it fixed.

 

Just thought I'd add this.
I was getting a P2195 (O2 sensor stuck).
After following this tread and others I checked the PVC and cleaned it.
Then removed and checked the ERG with a vacuum.
Now all is well. Not sure what it was. Engine runs smooth and does not
set code. I too first replaced the O2 sensor. What a waste.
No wonder many parts stores are low on right front O2 sensors.
We need to get the word out. It's not likely a stuck O2 sensor.
Scott

 

I have the same problem but can't find a vacuum leak any where any help replacing the o2 sen worked for a little wile but the problem just came back but worse