This is a strange intermittent problem that's been occurring over the past year. My 05 Accord has about 130k miles and I'm probably the 4th owner. About a year ago DTC P0139 tripped on the car shortly after I purchased it, so I had the B1S2 O2 sensor replaced with an NGK unit from Amazon. I could immediately tell that the car had more power after replacing the faulty O2 sensor.
A few months went by and the same DTC tripped again. Thinking I was sold a phony NGK sensor from Amazon, I bought an authentic Denso O2 sensor from Oreilly's and had it installed in the cat. After that was installed, the car immediately felt faster and the CEL turned off.
Now 4-5 months after that O2 sensor was installed, the same DTC has reared it's ugly head again. After some searching I found this TSB that Honda released 7 years ago. Could a software update be the solution to this intermittent DTC? I went to my local dealership and they said to perform a software update on the ECU would cost $155 which I think is rather outrageous.
Anyone else experienced this problem or know a possible solution?
TSB:
https://f01.justanswer.com/freefallin2005/6083a811-f6c3-48f9-862a-25ba0dae1e1f_A14-001.PDF
Pray a software fix does it, if not it could be a bad catalytic converter too
Thanks Scotty! Before I shell out $150 for a software update/diagnostic fee @ the dealership I'll try some Royal Purple fuel cleaner. Saw you used it in on a vehicle in Rhode Island and made a big difference. Fingers crossed my catalytic converter doesn't need to be replaced