califcamper

Hi,
I have an 02 sensor code coming up, actually had upstream and downstream codes.
I unplugged upstream 02 sensor to see if it would drive any better, and it did, plugged it back in and it got worse to the point of super bogging. So I unplugged the upstream, (didnt do anything with downstream), and it drives better.
I'm assuming since both codes are coming up bad, they probably both need changed.
My question is, is there a way to know if its the cat converter instead of the sensors? I guess im afraid of installing the 02 sensors and having
it be the cat converter after all of that?
Or should I just start with the sensors, and go from there?
thanks for any help

ezone

The system cannot evaluate the cat as long as there are O2 sensor codes present.
Fix the sensor codes first and drive it. If the cat has a problem, the computer will check it out after the sensor codes are gone.


What codes did it have?

Sensor(s) first.

Use the correct sensor(s). OEM, nothing else. Look on your sensors for the brand name, either DENSO or NTK and get the exact same replacement.

califcamper

thanks for the help


had both
p0135
p0134


pretty sure I will go with the upstream first, just because it began running really bad yesterday (Im traveling at the moment from Kansas in Texas), I unplugged
the upstream because I wanted to see if I could get to a motel til I get this fixed. It definitely ran better, light still on, but its been fluctuating on and off for a while, think its been slowly going. But thanks for the advice I will go with that one first, then second, then when those are good, like you said it will tell me about a cat problem. thanks again, now goes the praying.....

sdaidoji

iTrader: (1)

one way is to remove cat, but not likely in a traveling situation...

ezone

I see no codes pertaining to the rear O2 sensor. Both of those codes are for the front A/F sensor.

P0135 is "A/F sensor (sensor 1) heater circuit malfunction"
P0134 is "A/F sensor (sensor 1) no activity detected"


I know what I'd spend my money on.

califcamper

replaced sensor with denso (it was the expensive one, shown for car,
now need to clear codes, did myself so I have disconnected the battery and will hook back up after about an hour.
Is that a correct way to clear codes? Read where that was the way to do without shops help.
Hopefully all goes well after that??

ezone

That should get the job done.

califcamper

well doesnt look like it did anything...
replaced sensor, unhooked battery, cleared codes
drove ok for about 25mins, no light, then it started blinking (engine light),
did that went off, came back on 5 mins later, started blinking,
went off, eventually after about 4-5 times of blinking engine light, it stayed
on.....sucks, also still running messed up too.
will go get codes read again to see if it has changed any. Im thinking maybe other sensor?, cat converter shot?
When you said those codes are for A/F sensor 1, did you mean the upstream right? just wondering if I replaced what the po135, po134
codes were saying. I replaced upstream, its actually under manifold, front of
car, in exhaust pipe, is that correct?
thanks again....

checked receipt again, and it is definitely an A/F sensor for this car, total $250, denso, so it wasn't any cheap sensor?

ezone

Blinking CEL means it's misfiring, you will have P030x series code(s) now at the very least. You didn't mention having misfire codes earlier.


Yes the P0134/5 codes were for the upstream sensor.

califcamper

yeah had some misfiring issues at the beginning with the upstream
code, then replaced plugs (NGK), they went away then upstream
came back or basically never left, there was about a thousand miles after plugs that it cleared, I had a friend check codes after light was gone and it said misfiring codes pending but the p0135 and 134 were still there. Car was running
good at that point, although eventually light came on and stayed on. My friend said check into what those codes are and I saw it was the upstream sensor.
Thats where I was at about here a week and a half ago, when car was getting worse and worse. When it got really bad I unplugged and it ran a little better seemed convincing, but I did check the upstream sensor with a multimeter and it
showed burnt.
This morning, the upstream sensor code was gone, but the number cyl 3 then 2 showed misfire? I changed out both, spark plugs and coils, and helped and light went off for a little then came back on?
My question now is, this denso, a/e sensor has a white and green wire and 2 black wires, but I noticed the car actually has a white and green too, but on the bottom not on top like the denso, so they don't at all match up color wise. Its a perfect fit and all same connector, but should the green and white be matching up with car? I could get you the other colors coming off the car one is red and yellow stripe I believe but have to check. But I though that odd the white and green are mixed like that. It really seems like the car is just not getting the right mix of air and fuel and thats causing the misfires.
Im confused, sorry about the lenghth of post

ezone

The wire colors on the sensor almost never match the wire colors in the car harness connector. Not a problem.

AFsensor/car
Black / white,
black / green
white / red
lt green / red yellow





If there are no codes for the sensor now, the computer must at least be happy with what it sees as far as sensor activity.

If you think the sensor is still causing the running problem, simply disconnect the sensor and see how it runs. Yes it will set code for the sensor now but the computer will run at preset fuel injection rates (backup values).

califcamper

thanks again for the reply, you really have been a serious help.
that really helps with the wiring scheme, I almost went and started
cutting to match up correctly, glad I didn't.
I will reset again, and see what comes up, but as far as yesterday
no a/f had come up, just those 2 misfiring codes, perhaps
somthing else is going on with motor, if it continues to misfire, after replacing
plugs, etc..., I think I will take to shop and have it diagnosed, hate to
continue searching for something Im just not gonna see, maybe
a bad head gasket or something?

ezone

Get the freeze frame data for the misfire code(s) and post it here so I can check it out.

califcamper

will do,
Im currently disconnecting battery one more time to clear, changing remaining 2 plugs, did other 2 yesterday with misfire of 2 and 3 codes (and new coils),
after that I will start up, see how it drives, if it comes on again drive and retake to autozone for readout.
thanks again

ezone

Can you FEEL it miss, or did you just come up with misfire codes on a code scan?
If you can feel it miss, when do you feel it?
Idle? Driving?
Gas pedal mashed to the floor acceleration miss?




AZ here can't or won't get FF data with their cheap code readers. Gotta have a better code reader to get the data.

califcamper

Yesterday I replaced other 2 plugs, while doing it I disconnected battery. So now there are is no engine light on.
Car has a slight miss still when sitting idle, when I rev it up a little it goes away.
This all started with codes for missing cylinders, and the p0134 and p0135.
Originally I thought it was spark plugs, had changed them out with bosch about 6 months ago. Sooo, put in the recommended spark plugs about 3 weeks ago.
Light went out, and came back on when I drove to Texas. Assumed then, about
2 weeks ago it wasnt spark plugs, since I had changed them out. Figured it must be A/E sensor cause of those 0134 and 0135. Changed that out and that is what I did this last week. After changing that out, went and got the misfiring codes of cyl 3 and then 2, so figured for the heck of it, I will change those coils, (thought maybe it was just bad coils failing on acceleration?), then while there got new spark plugs. Pretty sure now this has nothing to do with any of that. Not sure about possible A/E sensor being wrong, although its the Denso 234-9017, but all I can see is that is correct too?
The best description I can say for it now, is if you have ever had bad gas, or water maybe in the gas? Where its like it can drive fine at moments, then
next when accelerating, like starting out, at about 20, I feel the cylinder misfire. It seems to be intermittent, there, then not. Very strange, On other cars I would think like maybe a coil is going, but Im sure its not the case here.
Maybe fuel injection system? Maybe something that controls the wiring of the
coils, like most cars have the wires, but as you know these are plugged in switches into each coil. Was thinking maybe if there is like a switch, sensor or something that controls those wires that plug into coils? All a guess at this point. Soo, right now its sitting, I got a temporary place here, and will move it
back to there tommorrow and on the way when the light goes back on, I will
check it, and post what it is. Another thing I was thinking, suppose its the harness so the new sensor is not getting any current from car? I will find out eventually what the problem is and
post. Strange thing is, I saw someone else post on here, same exact thing was happening, trying to find that to see if they ever found problem out.
Thanks again!!

ezone

Um, Bosch anything in the car is wrong.
NGK or DENSO for plugs.
AF sensor is probably ok.

I'll wait for you to post freeze frame data if you get it, I'd like to know exactly what conditions were stored when the computer set the misfire code.


Play with the gas pedal.
Misses mostly at steady speed?
Goes away when accelerating?


Unplug the wires from your EGR valve and drive it (Yes it will set more codes. Ignore for now.) See how it drives, see if the misfires go away.

califcamper

thanks ezone, will do, had to get situated here in the last 2 days have a rental, so car has sat at a walmart parking lot, til I can deal with it
will try the egr valve and freeze codes, Im assuming when u say freeze codes you mean prior right? (hopefully autozone can do this)
I did unplug the A/E sensor the other day just to see how it drives. Same as before, car drives better (not perfect), but don't feel miss. I am getting car
to where Im staying on monday, so will retry again then.Thinking maybe its that connector (male side), maybe a prob metal probes?
I will not give up!
thanks again.

ezone

I didn't say anything about replacing it. Just unplugging it.

Freeze Frame Data is a set of data parameters that are stored at the time a code is set. Not all codes and situations cause the data to be stored, but most do. The data allows one to get an idea of what the engine conditions were when the code set.

Example of how this is helpful:
9 times out of 10, a misfire code that sets at idle is going to have a different cause than the same misfire code set at 3000 RPM driving down the road.


FF data would have these

Fuel Sys 1 Status:
Fuel Sys 2 Status:
Calc Load: xx.xx%
ECT: xxx degrees
STFT: B1 +/-xx.xx%
LTFT: B1 +/-xx.xx%
TPS: xx.xx%
RPM: xxxx
VSS: xxMPH

Maybe some other data parameters too.


I doubt AutoZone will be of help. I know they don't get it here at my local store.... because that helps them sell more parts. They don't make money by selling the right part the first time.


What are you calling an A/E? What does AE stand for?

califcamper

current diagnosis, after replacing the A/F sensor, (sorry A/E was in error) car randomly misses at about 2000 rpms.
today I unplugged the new A/F sensor, car then has no miss at all, drives
98% correct, of course the engine light is on, due to the sensor being unplugged, but when I plug the a/f sensor back in, miss starts up again after
about a minute of driving.
I do remember all codes that have been shown since this started were random misfire codes of all cylinders, and P0134 and P0135.
I really thought I had this fixed with new A/F sensor?? Frustrating, any ideas?
Assuming the new A/F sensor is good, could it be the downstream sensor? Or are the P0134 P0135 only for upstream?
It seems when I have the new A/F sensor plugged in, something is making the car's air-fuel mixture to go way off causing the misfire?
I will try and unplug the egr valve tommorrow and see how it runs.
Thanks for the help!

ezone

Reconnect all O2 sensors and clear the codes.

Disconnect EGR wiring connector and test drive.

califcamper

thanks again ezone

cleared codes and connected o2 sensors

disconnected egr valve sensor

cars has no miss now and runs good with that unplugged

so car runs the same now (good) with the a/f sensor unplugged or the

egr unplugged? Since the a/f sensor is new, can I assume the egr is

probably bad?

ezone

EGR valve itself is fine.

The EGR passages are clogged.
The cylinders that do not have the misfire codes will be completely blocked with carbon buildup in the EGR distribution plate and intake ports. The cylinders that have less blockage are the ones that are getting the misfire codes.

Time to pull the intake manifold off to clean them out.

Check out this thread (I know it's long but start at about post 62) https://www.civicforums.com/forums/36-mechanical-problems-vehicle-issues-fix-forum/345718-2003-ex-misfire-p0300-p0301-p0303-p0304.html

califcamper

ohhh geeez
was hoping it wasnt something like that
is that something that is possible w/o a shop?

you don't happen to be in Houston by chance??

thanks for the info for sure, I greatly appreciate that.
wondering if this gas that has ethanol is helping the
clogging? I was in NY for the past 6 months and all
the pumps had 10% ethanol in the gas, occasionally
would see ethanol free, and I would try and fill it there
but had no choice 75% of the time.
Actually the intake manifold has 200K on it (2nd motor)
so I suppose its not that bad.

thanks again, and will let you know if I give this a shot
appreciate it!!

sdaidoji

iTrader: (1)

clear them every once in a while... like you said, 200k is not bad...
we wipe the rear end at least once a day, right?

ezone

Sure.
AFAIK, fsckewe didn't do his in a shop.

Most of the work is done from above, save for 3 10mm fasteners that secure the plastic intake to some brackets underneath. I think that's about all that is done from underneath.....unless you drop a lot of stuff.

It really doesn't take all that long if you know what you are doing.
I'd think a rookie could probably do this in a half day IMO if he has all the necessary tools on hand. (I can do the job in far less time.)
No, sorry.
We have corn where I live. Ethyl Alcohol.....Ethanol country, if you will.
We have nothing but Ethanol here, I can't remember the last time I could get plain gas here without Ethanol.
IMO the Ethanol has nothing to do with it.

It's simply normal carbon buildup that occurs in most EGR systems, since it IS using exhaust--and exhaust naturally contains carbon (soot).

Time, fuel quality, driving habits, and mileage all contribute to the issue of carbon buildup.


In my world, EGR cleaning is considered periodic maintenance.

If you are staying in Tejas, you will need to get it taken care of. They do emissions testing there AFAIK. Probably similar to testing done in Cali, or it could be different.

Some engine/manifold designs allow for relatively little buildup before it causes issues, some designs have room to go a long time before service is needed.

I've had customers that needed this done as frequently as 40k (on an 02ish Odyssey).
Sounds about average mileage for this to happen IMO.


YW

califcamper

Yeah should be able to do it, have done alot of
work to cars, will post how I did it, and if I have any
questions will ask. Hopefully this will help someone
else if theyre thinking of doing this.
THANKS AGAIN!!

sdaidoji

iTrader: (1)

glad it's back

woops, it's not yet back...

califcamper

Hey E, are thera any gaskets I need to get here before starting
this, or are they all reusable mostly? I read other post and was a little
confused about that.
Also, is the valve cover coming off for this?
thanks

ezone

Replacing gaskets is always preferable, but not always necessary. *hint hint*

Not necessary, but may be helpful.