A/F sensor relay

Not long after buying my truck, exactly at 100k miles, I got a P2241 code so I replaced both upstream O2 sensors with new Densos. I thought it had solved the problem and then the code came back a couple of weeks later. Then I thought maybe the problem is the URD harness extensions (I have headers), so I swapped those around, and sure enough the same code still came back. The only thing left for me to check is the sensor relay, but I doubt those go bad very often. This has me stumped because I can clear the code and it’ll be fine for a week, and then it comes back.

I do remember when I bought my sensors from Rock Auto they had two different part numbers made by Denso that they said fit my truck (upstream). Which one is the one that is supposed to go in the 4.0 V6? The stock ones I took out had a squared off tip, and the replacements had more of a tapered tip. If the problem is the sensors though it seems like I’d be getting a code for both of them?

 

I don't know about URD and how their product could be involved, so I'll set that aside. URD-wise people might chime in.
Check out the following URL. Error Code is different, but the concepts in this discussion might help shed some light.

https://www.motor.com/magazine-summary/diagnosing-o2-sensor-heater-circuit-failures/

Also assuming you bought the right sensor from Rock Auto.

 

The rep from URD said to swap the harness extenders around, and if the problem goes to the other side I’d know that’s it. I did that, but the problem stayed with bank 2.

The sensors I bought were

$126 Denso 234-9026 Air Fuel Sensor

Denso 234-9026, which Rock Auto said fit my truck. Then later I looked at some reviews in Amazon and someone there said those sensors won’t work for the 4.0, that it needs

$133 Denso 234-9051 Right-Bank Upstream with 4-Wire 8.5” Option Air Fuel Ratio Oxygen Sensor

Denso 234-9051. I’m not sure what to believe. If I installed the wrong sensors it seems like I’d get a code from both sides, not just bank 2.

 

I would go to the following site and verify Denso air fuel ration part number:

http://densoautoparts.com/

There is a "contact us" section at the top of home page. xxx-9026 shows as being for the 'left" side, but they show nothing for the "right" - maybe they are both the same. Query Denso for an answer.

 

I tried that, but it says they only answer business to business questions, not questions from consumers. You must list a business name in the contact form.

I’ll probably just end up buying another one from the dealer.