Finally got my 09 SH-AWD 5AT to throw the codes when paddle shifting on some aggressive backroad driving.

To clear these, the GoPoint BT1 module worked just fine, but you can't do it with the car running - have to electronics enabled / but not start the motor turn to clear them.

Richie, do we have a solution for this yet?

Thanks!

 

It seems to only set during aggressive driving. The service manual test procedure for a manual trans is 4th gear 50-75 wot , then decel with no brakes and see of it codes. I tried larger Defoulers, still sets..... Need a fix ASAP !!! Lol

 

No size of defouler can fix this codes throwing problem.

The problem is that, without all the cats in place, the O2 sensor is measuring little change in residual O2 content, and thus isn't sending the highly varied signal back to the engine control computer.

The only solution is either to install back all the cats, or to have a module that can simulate the same highly varied O2 signal that can feedback to the control computer.

 

Ed - if your logic applies, then wouldn't one rationalize diameter defoulers on sensors 1 and 2 would simulate this condition?

 

So it's looking like PCDs are going to require o2 simulators? Damn, I just got a forced education on these with my a 99 Maxima I bought (and subsequently sold) as a work car. Definitely don't want to deal with these things again.

 

Code P0139 is problem detected at driver side rear (downstream) O2 sensor, and code P0159 is problem detected at passenger side rear (downstream) O2 sensor.

This is how the upstream (US) and downstream (DS) O2 sensors work.

The ECU uses the upstream O2 sensor to detect the residual O2 content in the exhaust gas, and adjusts ignition timings and fuel injection pulse widths accordingly in order to achieve the 14.7 stoichiometric air–fuel mixture ratio.

The ECU uses the DS O2 sensor to monitor the effectiveness of the catalytic converter (cat), by comparing the DS O2 signal with the US O2 signal.

If the DS O2 signal shows significant reduced O2 content when compared with the US O2 signal, then everything is a OK, because the cat is working properly by using residual O2 to further oxidizing harmful pollutants (CO and NOx).

However, if the cat is defective or "missing", the DS O2 signal will be identical to the US O2 signal since no additional O2 in the exhaust gas will be used up by the unavailable catalyst action.

Therefore, since the ECU uses the US and the DS O2 sensor signals in two completely different ways, don't expect the trick that works for the US O2 sensors will also work 100% for the DS O2 sensors.

 

I'm sorry... What "trick" would you be referring to? You don't need to trick the primary af sensor. And Honda/Acura no longer designates the primary sensor as an oxygen sensor, but an AIr/Fuel sensor and the secondary as the o2sensor. And the reason it's harder to trick the secondary sensor is because the sensor no longer reads like the traditional 4 wire sensor. As for bank 1 being drivers side and bank 2 being passenger side, you would be incorrect. If we took the engine and mounted it longitudinal bank 1 would be the passengers side and bank 2 would be the drivers side. Front bank and rear bank is how Honda designates 1/2. Not to be a douche bag..... But I am....

 

^^^^^

Same shit, different names.

The fact that Honda uses the name "air/fuel sensor" rather than "primary O2 sensor" or "upstream O2 sensor", doesn't mean that the air/fuel sensor functions differently than an O2 sensor.

The air/fuel sensor still detects residual O2 content inside the exhaust gas, and the ECU uses this info to adjust ignition timings and fuel injection pulse widths accordingly in order to achieve/maintain the 14.7 stoichiometric air–fuel mixture ratio. This is exactly what the O2 sensors are designed to do, before Honda changes the name "O2 sensor" to "air/fuel sensor".

An O2 sensor detected residual O2 content inside the exhaust gas, regardless of whether it's a 4-wire design or not.

With a 4-wire design, the extra wires are used for the heating coil, so that the O2 sensor can get to temp. faster during initial engine startup for faster closed-loop engine operation and thus lesser emissions.

The signal wire still sends the same highly fluctuated rail-to-rail O2 content signal just like all other automotive O2 sensors, or air/fuel sensors, or whichever names they are being called.

The terminology may be different but the overall operation is the same.

So you are saying that the traditional 4-wire O2 sensor can be tricked, but this non-4-wire O2 sensor cannot ?

 

These codes are indicative that the car is unable to adjust the fuel mixture - and will always error on the side of "go rich".

What we're uncovering here might be part of why I'm so underwhelmed with the bolt ons. if the O2 signal coming back with too much O2 in the stream - it's signaling to the computer is saying "go rich, go rich, go rich" then the flow gains are being cancelled out by drowning the cylinders.

What we want is the sensors to read rich, so they tell the engine to go lean. If the spacer on the secondary is TOO restrictive, which is what I'm interpreting these codes as meaning, then there's power to be unlocked (and codes that can be avoided)

My thought it, a small spacer on the first sensor, would give some resistance to the equation - the first sensor is reading a live stream, and the 2nd sensor has a long 90 degree hook now in order to read it.

Just brainstorming, but maybe instead of trying to get the second sensor spacer corrected, adding a small spacer to the first sensor would achieve the desired effect (or make it all worse, lol).

 

Ok, let's all sit down and try to see if we can get this problem permanently fixed, which in my opinion is highly unlikely since even resourceful aftermarket tuning shops are still unable to do.

But first, we have to understand how this Honda feedback control air/fuel/exhaust system works.

Signals from the upstream (US) O2 sensor are used by the ECU/PCM to adjust the ignition timings and fuel injection pulse widths in order to achieve/maintain the optimal 14.7 stoichiometric air–fuel mixture ratio for complete fuel combustion. By messing with this US O2 sensor, one can make the engine run lean or run rich accordingly.

This one O2 sensor setup was all that required for automobile engine operation prior to the OBD-II requirements.

So came the OBD-II regulations. One of the main requirements is that failure in ANY emission related component MUST turn on the "engine" warning light and set the appropriate fault codes.

Since catalytic converters (CAT) belong to the emission system, there must be a mean to monitor their effectiveness. The universal solution ends up to be the addition of the downstream (DS) O2 sensors.

Signals from the DS O2 sensor are never used for the engine air/fuel control. They are used solely to monitor if the CAT is bad or "missing". The ECU compares the US O2 signals with the DS O2 signals to determine how effective or ineffective the CAT is operating, and to trigger the "engine" light and fault codes if necessary.

The CAT uses residual O2 inside the exhaust gas to further catalytically oxidize harmful pollutants. If the CAT is missing, no additional O2 will be used inside the exhaust gas; then the US O2 signals will be very similar to the DS O2 signals. Being not known of the missing CAT, the ECU will determine that the CAT is bad and set the "engine" light and throw some fault codes as a result.

In my opinion, the only permanent solutions are either to modify the ECU firmware to ignore the DS O2 sensor signals, or to build a device that reads and modifies the US O2 signals, then feed the modified signals back to the DS O2 sensor's signal wire to fool the ECU.

As a side note about the multiple wires for the O2 sensor. The 1 to 2 wires setup is the most common. For the 1-wire setup, one wire is for signal, and the metal body of the sensor is the ground. For the 2-wire setup, one is for signal, and the other is the separate signal ground.

Nowadays, due to the stringent Tier-x emission requirements, an electrical heater coil is added to the O2 sensor so that the sensor can get to operation temp (=very high temp) quickly during initial cold engine startup in order to reduce emissions. This is the 4-wire setup, with the 2 extra wire being the power source and power ground of the heating coil.

But the signal output information of these x-wire setup O2 sensors are all identical.

 

I'm pretty sure the ECU logic is doing a differential equation for fuel delivery based upon the data received from the MAF and then the O2 from the exhaust sensors. It wants to know how much fuel to give it and time the engine based on air in, but verify that it chose the right conditions by the exhaust. So we have another variable in play - MAF readings.

 

^^^^^

Oh yes, definitely.

The ECU is using data from the MAF and the throttle position sensor for course adjustment (of ignition timings [advance/retard] and injection pulse widths [=fuel delivery]), and data from the upstream-O2/air-fuel sensor for fine adjustment, in order to achieve/maintain the optimal 14.7 stoichiometric air–fuel mixture ratio for complete fuel combustion.

You know, I'm kind of confused.

The 2 fault codes you mentioned P0139 and P0159 are related to the O2 sensor circuits of Bank-1 Sensor-2 and Bank-2 Sensor-2, which are the downstream O2 sensors responsible for monitoring the CAT functions. They have nothing to do with faults indicating that the engine is running rich or running lean.

If you see the following OBD-II codes, they are the ones that are related to the engine running too rich or too lean :

P0170 Fuel Trim Malfunction (Bank 1)
P0171 System too Lean (Bank 1)
P0172 System too Rich (Bank 1)
P0173 Fuel Trim Malfunction (Bank 2)
P0174 System too Lean (Bank 2)
P0175 System too Rich (Bank 2)

 

I have a Honda-Guru dealer mechanic (20 years) friend who I turn to when I get stumped. He confirmed the following:

http://www.obd-codes.com/p0139


This involves the rear oxygen sensor on the driver's side. This code indicates the engine air fuel ratio is not being adjusted by the oxygen sensor signal or the ECM as expected to do so, or not adjusted as often as expected to do so once the engine is warmed or under normal engine use.

What I've noticed, is I can be at WOT just chugging in 3rd gear, and when it hits 75-80, it falls on it's face for about a second; almost like a slipping clutch would feel - and then regains power. It's like something is looking for validation in the fuel / ignition and it's just dumping fuel.

 

it would be interesting to see what the power curve looks like on a dyno.
I wonder if you can see the dip at third

 

Ok, trying to think deeper.

Everything is good when the CAT's are in place; but when they're removed, the ECU starts to throw fault codes. So the only thing that has changed is the pair of CAT's.

The CAT only functions as a catalyst to further oxidize harmful emissions, it doesn't take part in the engine air/fuel control mechanism.

However, when the CAT's are in place, the O2 content data sent out by the rear O2 sensors will be very different from that sent out by the corresponding front O2 sensors. But once the CAT's are removed, the O2 content data sent out by the rear O2 sensors will be quite similar to that sent out by the corresponding front O2 sensors.

I wonder if whenever the ECU detects that if any of the CAT's is failing (or missing), it will start messing up the engine air/fuel control mechanism ?

 

Right - but the ECU is looking for numbers to verify engine state. With the catalyst gone - it wouldn't be validating the running state with sensor readings that made sense, and maybe trying to go into some kind of "test loop" where it generates conditions and looks for levels? I dunno.

For everything that's done to this car, my thought is it should be making much more power, and the only thing in the way is the ECU at this point. Kind of missing the J32A simplicity here...lol.

 

The two codes being thrown are set because of how slow the secondary o2 sensors are responding to a decel scenario. If you've noticed the codes will usually set after you beat on the car,then decel and if driven long enough after the code is set without beating on it and deceling with the engine the engine light will turn off(with a code still stored). Prior o2 sensors and ecu's were happy seeing a steady .5v at the secondary, but there was no way to detect if the sensor was responding fast enough, which is why using a spacer/defouler would cure Cat codes. Our issue is when that throttle plate snaps close the air fuel is rich then leans out, and since our secondary o2 isnt directly reading in the exhaust stream, the ecu sees the sensor is still reading A richer reading instead of the leaner exhaust mixture we have the slow response code set. There's a specific time (milliseconds) that the o2 should switch, since we aren't meeting that specific time window we need to figure out the time window and how to reach it.

As for the power being affected, I haven't felt a surge, and it seems to pull just as hard with the light on or off. It's Definately annoying when people get in my car and the lights on, but I'm used to it for now.

 

^^^I had the P0400 code originally (IIRC) after installing the high flow cats...installed the 90 degree defoulers and BAM, no more. Then, yesterday...P0139 for me too.

I'm a 3G though...but would love to find a solution. I wonder if using a small (rigged spark plug defouler, as I've seen) on the 1st sensor would bring the levels between the 2 back in line, as mentioned.

Either way, subscribed for a solution. And just to be totally clear, this P0139 BANK1 SENSOR2...is that the front or rear cat? Please!

J.

 

Subbed installing my pcds tomorrow on a tsx v6 hopefully no codes for a while. I like to drive my car pretty hard so I'll probably be getting them.

 

Supposedly the defoulers on the pcd will keep you from getting the code. I have a bluetooth adapter for my OBDII port and was able to delete the code with car off (thanks to this thread). I guess I'll see how long it'll stay off for.

 

Lets go back to the basics....

did the PCD's come with a defouler...???

I have a 3G and had installed the PCD's without a defouler and got the same codes pop up....couple things could be wrong here:

1> the O2 sensors are loose....tighten them up
2> the defoulers are clogged....run some seafoam

I ran the PCD's with the defoulers for almost 3 years without a code....i recently started getting this code back and it cleared once i ran seafoam in my gas tank + intake (vac port) + engine oil....

also the bottom sensors as mentioned do all the CAT functions and the TOP do all the fuel trimming....hence you installed defoulers in the bottom sensors to "fool" the ECU as if the CATS were there....

 

I agree, I ran the high flow cats with no defouler for a week and got the P0400 one showing that not enough was being cleaned out...then put the defoulers in last week, then this week started getting the 139 code which says slow response.

I wonder if one of my sensors was on its way out anyway and running it for a week with no defouler finally killed it. I ran seafoam thru the gas tank last week too.

 

^^^ you might wanna run some thro the vac port as well Jer....and how much seafoam did you run ??? I run around 1/2 can of seafoam (8 oz ?) when i have 3-4 gallons left for max cleaning

 

Yeah, I'm due for vac line...I've done that though, and tank of gas, usually almost empty, about a quarter tank I put in 1/2 can.

Hmmm...well I had zero CEL's with high flow and NO defoulers. IF I drove really hard, this would kick out.

So got the defoulers and driving hard or not, I no longer got that code but got this one instead, clear the code and came back within 20 minutes of driving (not hard driving either).

 

Ok, so I've been going back and forth on this. Change the O2 sensors?!?! No, that can't be...

What I am thinking is this:
I had the P0430 code, which we all agree, was a problem with too much badness going throught sensor 1 and not getting picked up by the cat and hitting sensor 2.

Installed High Flow cats and I was fine, no CEL's when driving chill. Hit it hard, P0430 WITHOUT A DOUBT.

Ok, installed defoulers. P0430 is gone...doesn't come back, never comes back. For a week, I get NO codes. Then, all of a sudden, P0139...rear downstream taking too long for a reading...reset and drive like a maniac, NO CEL...because enough of the fouled air is getting to downstream O2 sensor. Drive relaxed and slow, and it's back within 15 miles. Now, this week and finally today, end up with P0139 AND P0159 pop up.

So, likelihood it's BOTH O2 sensors taking a shit at the same time? Slim.

Confirmed with Sharskbreath that he's got zero codes...so I'm wondering, due to the PCD's having NO restriction, maybe they allow enough of the fouled gases to make their way into the defoulers to not get the CEL?

So, my 2 solutions are this:

EITHER:
Get the spark plug defouler that you drill out so it's VERY short in comparison to the 90 degree defouler...to put the downstreams about 50 percent closer to the bad gases...too close you get the dirty air code, too far you get the too long to get reading code. Make sense?

OR, get the spark plug defouler and drill it out and put it on the primary O2 sensor (a lot easier)...I am wondering if this will offset the extra distance of the downstream to get a reading since the first sensor will detect less shit going past it. I might give this a whirl...try it on the front sensor first since it's super easy to do while the primaries are on the car.

Regardless I'll try and soak my O2 sensors in gasoline to get ride of any built up crud if i do have to pull them.

I'll keep you guys posted if I have any luck. I don't want to have to do this multiple times.

OH, and I too had that same issue...you punch it and are accelerating at about 80 or so, and it feels like your traction control kicked in and cut gas for a second. Yuck.

IF YOU HAVE THIS PROBLEM AND ARE LOOKING FOR A SOLUTION, PLEASE DO TAKE THE TIME TO RESPOND TO MY OPINION AND LET ME KNOW WHAT YOU THINK OF MY HYPOTHESIS. Thank you!

 

I was running the RV6 PCD's for 3 years and not code....

I have those 2 codes right now....but if I were you, instead of all the trial and error i would just contact Richie and get the defoulers he makes/provides with his PCD's

 

This is happening with Richie's defoulers installed.

 

^^^ I think he got some from Amazon or ebay if i remember right, think he had mentioned something about that in his progress thread.....

 

Yes sir, but ALL the guys in this thread other than me have the Richie defouler. I promise, I purchased one of the 90 degree ones that are VERY similar.

As promised, my first step in troubleshooting today...
here are my codes

went to autzone and bought spark plug "non" foulers...

drilled out one pocket with a 1/2" bit...

now, on front, not enough room to work with due to the passenger side fan so could only do a 1/2 of one. On the rear, I installed both defoulers mounted to each other.

here is the rear


I'll keep y'all posted of my results. At this point it's all just try this or try that to make informed decisions on a final solution here. Since I now have both front and rear codes...and 2 different lengths of upper defouler here, we shall see how it ends up. Moving the upstream back a little to offset the downstream reading was suggested here...can't take credit for that.

Reset ECU, let's see how we fair. Next steps...if front code comes on and it's due to not enough "defouling", I'll opt for a 90 degree one. If rear AND front come back...I'll opt to move the shorter defoulers to the downstream and take the 90's out of the mix.

J.

 

Jer, i think more than the bend, whats important is the bore diameter....

but awesome work....let us know how this works out

 

Yeah true...didn't think of that, was thinking it was likely also the additional length of it.

No defouler seemed like it spits out a dirty code...90 degree long defoulers seems to spit out a too clean this ish is taking a long time to read code. We shall see.

BEST CASE...no codes come back!

 

hope no codes come back...

 

So I dont have an Iphone so no go point and I got a CEL after 5 days of driving will it go away on its own or do I have to buy a code reader, if I have to buy one which one do you guys recommend(budget minded please)

 

do you have an android?!?! if so, bluetooth reader from amazon for $20 shipped and then "TORQUE" app from the market for 5 bucks. AWESOME.

If you're strapped for cash, brother, do autozone they read for free.

 

Yea I am an android user. Will that app clear the code??? bc I was told some code readers just tell you what they are without clearing them.

 

3G TL-S here and I been running Richie's PCD's with his provided 90degree defoulers and like swoosh mentioned i too never got a CEL to come on and this was without even doing a ECU reset either as some suggest to do....then I stepped into a JnR tune and now every once in a while I get running rich codes which is normal as I am running rich and also don't care about the CEL no more as I have also deleted my EGR.....but yeah when running just PCD's prior to the JnR tune I had no issues as well.......

rockstar how many miles do you have and also is it possible that maybe you have bad sensors or has that been ruled out.

 

^^^Definitely not ruled out. I'm at 84k...Seems like pretty bad luck for BOTH of them to have taken a shit on me....BUT after defouler install on downstreams for 1 week I had NO CEL's...
Then 1 on the rear lower and a week later the front lower joined it. I've read that you can sit them in gasoline to clean them...which I may try, or rather than have to un and reinstall them, I'll just buy new ones.

Miscura, yes, torque allows me to clear them.

 

Anyway...no dice on the upstream O2 sensor with the small defouler...BOTH codes came back today after a 20 mile drive. So, back to the drawing board...I'm CONVINCED that for the amount of bad air making it's way through, the defouler moved the downstream sensor too far away from the stream...under high rev/wot conditions, no code...driving chill, code. Opted to use my modified spark plug "non-foulers" on the downstreams.

My REVIEW on messing with the upstream sensor...DON'T...it sucks...at idle the car was bogging itself...sputtering and almost turning off...I'm guessing, running RICH. While driving and downshifting the car jerked violently a few times, I'm guess with unburned gas. Don't mess with your upstream. It won't solve your downstream issues.

Here is the 90 degree defouler I had on there...swapped out...all in all, to remove and reinstall all and wrap, took me 2.75 hours. Not bad at all.

soaked the downstream sensors in gas as i read that would clean out some of the gunk

and here is the jpipe pre wrap...and primary wrapped...I DID find that where they spot welded the heat shield on, there was a slight leak and possibly the heatshield would vibrate against itself when cold...it was annoying...so I put a piece of wrap under it, put some exhaust sealant on the hold and wrapped OVER the whole heatshield.

Jpipe wrapped

and front reinstalled

rear reinstalled


Honestly, I preferred getting the P0430 code when I'd drive it hard than these 2 codes from driving chill.

Anyway, I'll keep you all posted on whether or not this solves my problems.

J.

 

Agree, don't mess around with the upstream O2 sensors. They provide crucial exhaust gas residual O2 information to the PCM/ECU to control the fuel trim for proper engine control operation.

The downstream O2 sensors play no part in such engine control operation, and are used purely to monitor the catalytic converters.

 

Right, which makes me feel like I could totally live with the CEL.
Now, this morning, bad news, faster than ever, got BOTH codes again.

What does this tell me?!
No defouler P0430 Code
90 degree defoulers added, no codes for a week.
Then got rear downstream code.
a week later got front and rear code.

After all this, I'm REALLY thinking that the harsh conditions over the course of 9 years...make wiring brittle or the sensors are just caked with crud. At 84K miles, it wouldn't be totally unheard of for the O2 sensors to be bad anyway...and the timing of how no codes then little by little pops up faster and now both are spitting out the code immediately.

I'm seriously thinking, I may go ahead and swap to 2 new downstream sensors. And will likely wrap the rest of my exhaust.