My brake life has not been as bad as yours, I have almost twice as many miles on my van (167,xxx miles) as you. Here's a summary of my brake repairs:

On the rear:
Replaced the pads four times and the rotors once, and I recently changed the rear calipers.

On the front:
Replaced the pads five times and the rotors four times.

I have found that applying silicone brake lube ( I use Sil-Glyde) under the anti-rattle clips reduces the amount of build up of rust and crud under the clips, allowing the pads slide more freely.

Also cleaning and lubing the guide pins and brackets between brake jobs help to keep the pads from binding. I also make a habit of setting the parking brake often.

 

I installed drilled and sloted rotors F & R, stops better but pads wear quicker, I have a 1999 Ford Expedition, I tow with, on it's 2nd set of rear brks. original rear rotors 175K.
2nd set of rotors on the front. (aftermarket drilled & sloted) On our wonder filled Dodge
the rears wear twice as much as the fronts, the poportioning valve must be out of whack
and has been from the start. I don't have a clue how to adjust it or where it is.

 

I think someone drives the H&LL out of their van (me), doesn't take care of it (not me), and calls it junk when it doesn't last (depends on the day).

170k 3 set of pads/ 1 pair of rotors up front. Drilled/Slotted rotors don't wear decent pads quicker, actually quite the opposite (unless you're using garbage pads).

Buying good parts and doing the job right makes a big difference in how long it will last. You've also gotta remember you van basically uses a car brake system to stop a vehicle that weighs 1000lbs more, it's going to go through brakes faster then your expedtion, whose brakes were designed for it.

 

I couldn't agree with you more; the brakes on Dodge vans are an extreamly poor design, and should have been bigger. As far as pads go I find that no matter how much they cost they wear out quicker with the drilled and slotted rotors, on the many vehicles I deal with
no matter what brand they may be.
But this discussion is about P0038 again and again.

 

Never had an issue with d/s rotors, and my vehicles get driven hard (tracked on occasion), pads last far longer, brakes stay strong. It's possible you have underlying problems causing your premature failures. Like collapsed hoses to the front calipers.

On the P0038, Realize the wiring may have been damaged when the cat was loose, or may have gotten damaged when you changed the sensor. I know it's an obvious question, Did the sensor get plugged back in? Had more then one vehicle come in with O2 codes and new sensors, just to find the owner changed it and never plugged it in.
Here's the possible causes.
- Faulty Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2
- Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2 fuse
- Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2 harness is open or shorted
- Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2 circuit poor electrical connection
- Faulty Engine Control Module (ECM)