The truck is an 08 F-250 running an SCT programmer with the DPF / Cat delete. I'm told the truck has oxygen sensors and also told Ford did not use them on diesels until 2010 which would be the 6.7 engine. The reason for asking is I preparing to add an HHO generator to my 6.4, have used one on a 6.8 V-10 sucessfully. Question: 1) What is measured to determine regeneration? EGT..O2? 2) If it does have em does the programmer blind them so the regeneration process doesn't happen? The HHO gas increases the O2 levels in the exhaust causing the PCM to richen the mixture on gas engines decreasing mileage. Therefore, like on gas engines the O2 sensors must be electronically dealt with. So what I need to know is if the 6.4 uses O2 sensors or not. Thanks

There are no o2 sensors on any diesels from Ford. The sensors you're talking about are temperature sensors.

So it's the monitoring of air temps. which trigger the regeneration process? I noticed that sensors are fore and aft of the dpf (when it was still on the truck) and aft of each cylinder bank. So theres a massive amount of temp. comparison going on which determines regeneration...maybe?? And I'm also assuming the programer, when in dpf delete mode, is overriding the sensors so that regeneration doesn't happen like...they are there but the PCM doesn't see them.
Anyway thank you so much. I have talked to my local Ford dealer and SCT technical with confusing replies at best. And that's what makes this forum so valuable. My compliments. Thanks again.

You also have the pressure sensor that sits on top of the pipe between the catalytic converter and the DPF. It measures the back pressure at that point to determine when the DPF is getting restricted enough to trigger the regen process. There are several temp sensors all through the exhaust, measuring even entry and exit from each of the egr coolers. Those judge the efficiency of the coolers. Even if everything shows ok, it is still programmed to regen at the 3701 mile point (lots of people dont know that).

Very interesting. I had wondered what the third, not sensor like looking, item was around the DPF / Cat which required mounting in the new pipe along with the two temp sensors. They are all located in the same approx. location as when the DPF and Cat were in place. The replacement pipe came with all the fittings welded in place to receive the sensors. I can't help but wonder how long it took Ford engineers to figure all this out and have ready for production with enough certainty that it would actually work in the real world. Thanks again for your help.