O2 Sensors, Misfire, Catalyst damaging misfire.

Question: Do I have to replace all of my O2 sensors? Or is there some other cause? I suspect there is. I hope I am rite, O2 sensors are expensive. I have researched the forum and can’t find an answer.

01/04/13 P Codes taken from an Inova OBDII code reader from O’Reilly:
P0171 System too lean (Bank 1)
P0141 O2 Heater Circuit (Bank 1 Sensor2)
P0150 O2 Circuit (Bank 2 Sensor 2)
P1171 System too lean Bank A & Bank B
P0130 O2 Circuit (Bank 1 Sensor 1)
P0140 O2 Circuit No Activity Detected (Bank 1 Sensor 2)

01/03/13 I took all of the O2 sensors out and soaked them in Sea Foam for 24 hours. I then put them back in, but switched them from left to right and right to left. When I did this I noticed that the bank 2 sensor 2 O2 sensor looked different, it is skinnier. I have attached a picture of it. It is called Skinny O2 Sensor. Also you will notice that no activity detected moves from the passenger side (Bank 2 to the driver side Bank 1). I bought this sensor on rockauto.com back in October. It was the one recommended for my vehicle. It does fit both rear (sensor 2) connectors, so I know that it is not a front (sensor 1) O2 sensor.
I have attached a picture of a sensor that resembles the rear (sensor 2) sensor on the other side. It is called Fat O2 Sensor.

1/02/13 P Codes taken from an Inova OBDII code reader from O’Reilly:
P0130 O2 Circuit (Bank 1, Sensor 1)
P0141 O2 Heater Circuit (Bank 1 Sensor2)
P0161 O2 Heater Circuit (Bank 2 Sensor2)
P0160 O2 Circuit No Activity Detected (Bank 2 Sensor 2)
P0150 O2 Circuit (Bank 2 Sensor1)

12/28/12 I replaced the driver’s side coil pack. This eliminated random misfire, cylinder 4 misfire, and catalyst damaging misfire P codes. This I believe this was the original problem.

12/15/12 I replaced cylinder 3 exhaust valve which was bent by the dowel pin that goes between the air intake and the plenum that was knocked into the engine and chewed up in cylinder 3. In the process I replaced the driver’s side head gasket and all of the gaskets above that. This eliminated cylinder 3 misfire and the truck ran markedly better. This cost me $150.00 in parts.

11/30/12 I replaced spark plugs and wires, using the ones that Disco Mike recommends. I think the wires were Magnecore, but am not sure, they came out of Germany I think, they cost $70.00 and are 8mm. I got the specific plugs that Disco Mike recommends from O’Reilly, they cost $35, and have an iridium core or something like that. I believe it was at this point that I knocked the dowel pin down the intake and into cylinder 3 when I was putting the plenum back on. This eliminated no codes, but rather added a misfire in cylinder 3.

11/07/12 I drove the truck 300 miles with a catalyst damaging misfire in cylinder 4 home. This cost $80 in fuel.

1/06/12 My brother in law and I found a fuse that was blown controlling the Mass Air Flow Sensor. This eliminated approximately 10 P codes. We then put Sea Foam into the vacuum lines and drove it around until it stopped smoking. This eliminated not P codes.

11/4/12 I drove the truck 300 miles to get help from my brother in law with approximately 18 P codes. One of which was a catalyst damaging misfire. This cost me $100 in fuel.

10/10/12 I replaced both, bank 2 sensor 1, and bank 1 sensor 1 O2 sensors. This eliminated no P codes.

10/07/12 I replaced the bank 2 sensor 2 O2 sensor. It was loose; the wires had been hitting the drive shaft and were frayed and cut. This eliminated no P codes.

10/01/12 I changed the spark plug wires. This eliminated no P codes. Note: I did it without taking off the plenum. Way harder than taking off the plenum.

9/12/12 I bought the truck.

 

Replace the front O2's.
Clear the codes.
The fronts are the ones that control engine fueling, the rears are catalyst only, in other words they make sure the cats are working and nothing more, nothing less.
Multiple misfires would indicate the need for a tune up, blown head gasket, valve problem.
Since you already did all of that work try the front O2's.
Amazon has the best price on O2's.

 

I agree with Spike that the rear sensor are for catalyst monitoring, but they will still trigger codes, the statement that the fault moves with the sensor pretty much answers the question what the fault is. (even if it's new). The rear sensors are different from the front. Looking at the code list, I would replace both rear ones (after I made sure that they were plugged in and there was no liquid in the connectors). The P0171 and 1171 can be caused by air leaks in the intake system after the MAF, leak in the exhaust before the front O2 sensors, or a bad MAF sensor. The fact that they appeared between you removing the sensors and soaking them leads me to think that a vacuum or intake hose didn't get reconnected properly. Another thing to consider is "are the rear O2 sensors plugged into the proper connectors?" It is possible to swap the connectors left to right, if that happens it will confuse the ECU. This usually happens after a transmission R&R and the plugs aren't marked for left and right and get plugged into the wrong side. This probably doesn't apply but thought I'd throw it into the possibility mix (I had this happen on one of my customers car and it was a long drawn out diagnosis). HTH