2006 Accord 2.4 p0139 2006?
 

Ok, put new converter on and new o2 sensor like 3 weeks ago (did this because converter was bad p0420) anyway, now about 400 miles later throwing p0139.
No vacuum leaks, cleaned mass air flow sensor... No exhaust leaks... No wiring issues on new o2 sensor.....
Does anybody know real fix?? I read people trying different o2 sensors and don't fix anything. I guess the new o2 sensor could be bad but doubt that. Anyone have real success fixing this?

I've seen the front A/F ratio sensor (wide band O2) cause the rear sensor slow response code. Aftermarket sensors will give you nothing but aggravation...is the CAT OEM?

Have you tried to clean the MAF and the throttle body yet?

There is also a TSB regarding a re-flash of the PCM specifically addressing this code.

Let us know.

aftermarket cat. cleaned intake and maf sensor. how do i reflash the pcm????

You take it to your local Honda dealer and pay them 90-120 bucks...unless it has been done already, the service dept can look up the VIN to see what updates have been done.

But you may still have issues due to the aftermarket CAT.

im thinking it is a bad oxygen sensor, i was watching voltage and it went above 1 volt a few times. i ordered a bosch, the one in now is a cheap ebay one.

well new bosch o2 sensor rear. no luck. today i am putting a new front air fuel sensor on. my scan tool showing everything working right. i will post back after the new sonsor is replaced...
also, is there really a tsb out about flashing the computer for this fault? anyone have a link to read about it??

P0139 means the rear O2 sensor is having a slow response. This likely has nothing to do with the front a/f sensor. I highly suggest that you don't waste your money by installing a new a/f sensor until you do some more diagnosis.

Since you have a scanner, what do the long and short term fuel trims look like?

i will look tomorrow and post back, i am away from car right now. also do i just read them at idle or??????

Take a look at idle once the car reaches operating temperature for starters.

ok, st at idle about 3.0. lt about 4.0. when driving jumps from usually about 7.0 to 0.0 its stick shift and if i hit gas hard it will jump up to like 17. but drops real fast. lowest it went driving was like -4.7.... cruising at about 15% throttle sits about 5.0.. any of this tell you anything??? thanks

idle is about 720 to 850 rpm. its stick shift

ok, checked stlt trim again at idle. now it is st like 10.2 at idle lt is like 5.5 idle was 725.

Anyone???????????? Hello????????

So you've verified that the ECM/PCM has been flashed with the latest program?

yes. what about my stlt trims???

I'm not worried about the fuel trims right now, but that bosch sensor is junk...we get more techs that won't listen us. Use a Denso sensor, and california and non-california are different sensors as well.

bosch sensors are good and as good as denso.

Your fuel trims look good, so the engine computer is not having to add or remove a lot of fuel due to the a/f reading.

Is there a certain rpm where the CEL turns on?

not that i noticed. i changed the air fuel sensor so will see what happens, so far so good

well it has been at least 3 weeks and 600 plus miles since i changed the front air fuel sensor and i have NOT got a check engine light back yet. I am sure since I am posting this it will pop back on now :eek: but I think this fixed the problem. :D

Did this ultimately fix your issue?