I just bought a an E350 5.4 V8 Gas Van. When the sale was pending, the check engine light was on for O2 Sensor Bank 2 Sensor 2. The dealer replaced the O2 sensor twice, with multiple brands, and the code would not go away. I then noticed that under the van the CAT was previously stolen and there was an aftermarket cat welded in. They had a muffler shop check and hit the welds again. The code did go away and is driving fine for ~1,000 Miles.

However, soon after buying it, I decided to hook it up to a scan tool. I noticed that three readiness monitors will not turn green. O2, CAT, and (O2 Heater Core I believe). It would not pass even after driving it a combination of highway and city to this day. There is no check engine light. I did my best to follow the drive cycle recommendations. The fact that CAT and o2 monitors specifically would not pass made me re-suspicious of the initial problem.

On a hunch, I took an infrared thermometer and tries to measure if the CAT was doing its job. After idling for about 15minutes the CAT read about 350 degrees F. But after driving around the block for about 10 minutes afterwards it got up to 670 F?

1: Is that too hot for the CAT to be reading temp wise?
2: When checking, before the CAT, I could not get it to consistently read cooler than right after the cat. But it's hard as the temp sporadically jumps when the vehicle is running. Most of the time it actually seems like the temperature is HOTTER before the cat then after the cat.
3: Should I be concerned about the drive-ability of this vehicle? What other tests do you think I could do? I'm not worried about inspection as it's safety only - but the fact they are not turning green is ODD to me, and I'm wondering if there's still something going on that's exhaust/O2/Cat related...If there IS, I'd suspect it would throw a code. I'm also wondering if they somehow programmed it in their favor when selling the vehicle (because isn't it odd for readiness monitors to fail and NOT throw a code?)

 

I believe there is more going on than we at this time know.

I can't believe the dealership could not fix the problem. Without pointing fingers at anyone, this is going to take some time and testing to determine why the monitors don't run.

Not a good situation, and not a good position for the dealership to allow themselves to get into.
If they sold a vehicle that had known defects and failed to repair or disclose them to a buyer kinda leaves them in a bad position. Was the vehicle sold "as is" ?

 

The vehicle has a 3month 3k aftermarket warranty that is only drivetrain. It’s almost over with. Cat/emissions is not covered. If I can truly figure out what’s going on, then I can use that for some leverage if I need to with the “dealership”. I use quotes because it’s more of an individual that runs his business.

I’ve had a handful of opinions from master techs as well as “regular shops” - they all say that if there WAS an issue with the cat you’d feel it and know right away. I’m willing to let the readiness monitor issue go if I can confirm there’s nothing increasingly detrimental with the vehicle. Going to try and hook it up to a diagnostics software tool and have a colleague look at it this week. I suppose I can also try to check the pressure upstream of the cat from the o2 sensor to confirm it’s not clogged.