P0139 code again

[metalmoto]

04' with 163,000 miles. Replaced Oxygen sensor, problem went away for a year or so.
Back on again. But I noticed a pattern, the check engine light, would come on every time I'd fill her with gas. After driving about 3 miles, every time!

Going out now, with my new $200 diagnostic tool, to try and figure it out.
Hope it was worth the investment.

I will get back with the results.

 

[metalmoto]

Still trying to figure out how to use the new scan tool.
But it appears both rear oxygen sensors are not working.
Voltages stay high constantly.
Not going to run out a buy 2 new sensors yet.
Need inspection, smog test soon.
Please help?

 

[tommudd]

What brand did you use ?

 

[metalmoto]

What brand did you use ?

I don't remember. Don't think I ever replaced a downstream sensor on it.

 

[J33Pfan]

Make sure you used NTK/NGK 02 sensors only! You must change both up & down at the same time. I learned the hard way. check no exhaust leaks are present.

 

[metalmoto]

Well, I tried replacing the B1S2 O2 sensor. I couldn't get the other rear sensor loose. Immediately, I got a code saying the heater circuit on that sensor was bad. So I put the old sensor back in. Live data looks fine for all the O2 sensors. Just took a long drive, and it now has a pending P0139 code. It must be something else causing this code.
I am running out of time, for emission inspection. So I will have to let a mechanic figure it out.