So that's the acronym - NOX vs. NO, cool. I believe I have reducing cats. I replaced both original precats 4 years ago when I had a CEL. I can't remember, but I think the DTC was P0402. I was lead to believe that Ford skimped when the cat honeycombs were dipped in the chemical bath so they were prematurely failing. Before the replacement, I swapped the downstream O2 sensors around to see if the problem went away or followed a sensor, but the code persisted. The precats were replaced with OEM equipment. Later various posts suggested the problem could have been fixed with a PCM flash upgrade, but I had already replaced them. I still have the original main cat.
During the UIM/LIM rebuild I applied vacuum to the EGR valve and watched the valve stem move. I never did any tests while the engine was idling.
For the first smog test I drove the car to the shop using surface roads and revved (2000 - 2500 RPMs) the car for 10-15 minutes while waiting my turn. For the second smog test I drove the car on the higway and never shut it off before the test.
Do you think the OBD self tests not completing was a result of the precats/cats not being sufficiently warmed? I was told that even if the car passed emissions wise I would have still failed because the self tests didn't complete. This is what drove me to replace the DPFE since its voltage is input to the PCM wherease other EGR components like EVR and Air Pulse are controlled with PCM outputs.
Thanks for the input, hopefully this discussion will help others.
