Hey guys, this is a continuation of my previous thread "how to diagnose why i'm running rich" but started a new thread because I have a different problem now.

I once again have codes P0134 and P0154, both front O2's with NO ACTIVITY. (bank 1/sens1, bank2/sens1). I've gone through 3 sets of NEW O2's from AB, and here is what I've learned to date.

-The o2 harnesses receive power properly. (pink/white wire)
-The pins in each harness connector have checked out between the harness and ECM, continuity good. (other 3 wires)
-The connectors were thoroughly cleaned to dismiss oil/coolant leak dripping onto/in the connector and frying the o2. (we also zipped tied them up and out of the way and completely covered with electrical tape, hopefully dismissing this cause)
-We saw with live data that the most recent set of new o2's worked properly and gave readings once installed, and the truck went into closed loop properly and all was well. (the most obvious evidence of them working was not smelling straight fuel from the exhaust from running so rich)

So, I had properly functioning o2's in once again, no chance for oil or coolant to drip in/on the connector, and yet once again, within 3 days these o2's are dead or showing "NO ACTIVITY" and the truck obviously runs extremely rich in the default open loop. It could have killed these O2's (or went to "no activity") much sooner, but our check engine bulb is still pulled and I borrow a scanner.

What else can be killing my O2's? Can the sensor part that is plugged into the exhaust die from oil drips onto it? Can something through the exhaust kill the sensor? The new o2's were not killed by overfueling or richness because it ran great and didn't overfuel until there was once again no activity.

Any ideas or things to check is appreciated.
Thanks, DIIB

 

If you use a Connection Enhancer on the O2 sensor terminals it can kill (suffacate) the sensor. Did you use something like Stabilent22?

 

Like dialectric grease? I did use some dialectric grease this time, but the previous 2 sets of o2's were not given any.

For cleaning, we used brake cleaner (at the advice of a current LR master tech), dried it out really good, then used CRC electric parts cleaner, dried out really well again, and then some dialectric. It functioned great and properly with proper readings for a least an hour.
I need to get my check engine light bulb back in so I can know how long it worked properly. But each time the new sensors lasted no longer than 3 days.
I also find it hard to believe that we've gotten 3 bad sets from AB, but who knows? I'd like to cancel out any other possibilities and check everything possible before getting another new set in.

 

The o2 sensors aren't going to show activity if the engine is always running rich. they are only going to show rich. Perhaps something else is causing the engine to run rich, and the o2 sensors are reporting it correctly.

I've heard of certain types of silicone causing o2 sensor failures, such as silicone spray or old orange RTV.

 

So I just noticed that it says that excessive heat can kill them. I wonder if the original problem cause a restriction in the cats, and now the sensors are getting too hot?

 

I doubt it, because the sensors are rated to handle up to 1400F (if I remember correctly).

The o2 sensors DO show a reading even when rich and adjust the system accordingly (when functioning properly). When the new o2's were put in we could watch their measurements and adjustments, but once they are fried the ECM puts the system in default open loop at .449 (estimate off of memory) and THAT is when it runs rich and states NO ACTIVITY, meaning, the o2's aren't sending the ECM any info because the heater element in the o2 is seemingly shot.

I'm sure lots of over fueling from other reasons can/will kill o2's, but when the new o2's were first installed and running, the truck wasn't over fueling. Meaning, there was no sign of over fueling, no codes, and the system ran in closed loop. So if something else was causing the over fueling, it would have kept over fueling even with the new o2's. Am I wrong in thinking this?

I also have new cats and a new muffler, so the flow through the exhaust should not be the problem either.

 

When the ECM goes into Open Loop it does not stop the O2 sensor from working, it just stops making corrections according to the O2 sensor. Check the other obvious possibilties for running rich - air filter, leaking injector, Coolant Temp sensor. Have you pulled your plugs to look at them? Old-school way judge mixture.
If the engine was ever resealed with a silicone-based RTV this will kill O2 sensors. But even if they went bad, they are really just meant to fine-tune the mixture. They are not meant to correct something like a leaking injector.