Code P0133 keeps coming back

[Layla11242]

I've got an 03 LS and for about a year now I've kept getting the code P0133, it goes away on its own sometimes but never fails to eventually come back. I have replaced all four O2 sensors and cleaned the fuel injectors, and the car runs fine...
Anyone have any ideas what else this could be?

 

[joegr]

You probably need Forscan or similar to dig down to the details of what is happening.
Also note that the LS does not like most aftermarket O2 sensors, including Bosch.

 

[Layla11242]

You probably need Forscan or similar to dig down to the details of what is happening.
Also note that the LS does not like most aftermarket O2 sensors, including Bosch.

Thanks, I put the ford motorcraft sensors in but thanks for the note. I'll give an update when I get this figured out.

 

[Layla11242]

Sorry for the late reply, but I hope this can help anybody who seems to have this persistent p0133/p0153 issue in the future.

If you're buying Ford Motorcraft O2's, beware that Ford changed the part number for the 02's on this car and the new part number is not correct. I'd recommend avoiding motorcraft brand for O2's- or really any oxygen sensor labeled as upstream/downstream.

It turns out that there is no real universal upstream/downstream sensor and the left/right side are actually two different parts. I solved this by buying the NKT Brand instead, which offers the right and left side sensors.