Huntr1117

I've had this issue for a while now and I'm just getting annoyed with it now. About a year after LT install I started getting P0133 and P0153 codes. The car has Jethot Lts with emissions so I still have the EGR and AIR Pump functioning. Got a tune from MadZ28. I usually just clear out the codes and they stay off for a couple of weeks. I've searched and I know that they are the pre cat O2 sensors slow to respond. So I bought some new AC Delco 02 sensors and installed them. I made sure to be very careful with the install. Didn't touch the sensor with my hands or get any of the anti seize on the sensor. Drove it for a couple of weeks then the same problem again. It throws the same codes. Any idea what could be causing this? Could it be the tune. I don't have any burnt O2 wires and I used actual extensions instead of splicing.

Injuneer

Is it possible the outside of the sensors is being contaminated by oil, a hydrocarbon or exhaust? The exhaust is on the outside of the sensor thimble. The inside has to contain ambient air. The air enters through the wires. The sensor voltage is a function of the difference of the O2 content in the exhaust and the O2 content in ambient air. Anything that contaminates the outside of the sensor, where the wires enter, could be causing the problem.

I'd also question the use of anti-seize. Generally the sensors come with a conductive anti-seize compound already applied to the threads. Adding more just runs the risk of contamination, if that's what you did.

Then there's the possibility of contaminated fuel. The factory manual indicates "When DTCs P0133 and P0153 are set at the same time, this is a good indication that a fuel contamination condition is present. Do you ever use leaded fuel at the track?

Then there's the contamination of the sensors due to the use of silcone containing products like RTV for sealant in the inlet air tract or the fuel system.

And finally, per the manual "an exhaust leak 6-12 inches away from the HO2S can cause a DTC to set".

Poor wiring connections can contribute to the failure. Are your extensions high quality.

Huntr1117

I'll have to check the outside of the sensors for any contamination tomorrow. I guess that they could be getting some of the exhaust gases on the outside when my cutout is open, but I doubt that. I'll see if there's any oil or dirt in them.
The new Delco sensors I bought came with conductive anti-seize that I put on just the threads. I was very careful doing it.
I've never ran leaded fuel in my car. Could it just be old fuel? I drive the car a couple of times a month. I have added fuel stabilizer to the tank before but not in a long time.
I'll check for exhaust leaks tomorrow. Does it matter if they are before the 02 sensor or after?
The 02 extensions are from the ws6store. I think that they are from painless.

Injuneer

Do you always buy your fuel from the same source?

I'll have to look up the MSDS sheet for "fuel stabilizer" and see what's in it.