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Hello everyone,
I did my first ever Transmission fluid change , power steering fluid change,coolant flush and spark plug change. used all honda OEM for this except spark plugs - used NGK V power.
after these changes I can definitely experience the car is running smoothly and without any problems.
after changing the spark plugs, next day while driving on the free way, engine light came on and the code reads to P0420 which has something to with the cat converter.
my question: is this just co-incidence or any of above work can cause this?
has anyone seen this before after regular maintenance?

my car is honda civic LX 2002 Auto trans and has 112K miles on it.

This is my other thread for the work i did recently :

https://www.civicforums.com/forums/1...id-change.html

Thanks for reading.

 
Rep Power: 518

Coincidence, unless the engine had misfires or some other problem to cause the cat to go bad prior to this. At over 100k, it could just be time for it to go.

Are the plugs properly gapped at 1.1mm, and there are no other codes in the computer?

Erase the code and see how long it takes to come back on with the same code.

Exhaust leaks can cause false cat codes too, so make sure the exhaust is sealed tight from the engine to at least 2 feet past the rear O2 sensor.

If you do have to replace the cat and pass emissions tests to keep the car on the road, then OEM is the way to go, even though it is expensive.


HTH

 
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thanks ezone. there are no other codes. gap is correct.
one thing to add...after changing the plugs,I drove the car locally for abt 10 miles and the light was off. only when i took the car on free way,the light came in.to be very frank,i do not know what is misfire.
but can this also cause 420 code? and can the spark plug gap or too loose/tight spark plugs cause this?
has 420 nothing to do with the transmission fluid,coolant change?

 
Rep Power: 518

one thing to add...after changing the plugs,I drove the car locally for abt 10 miles and the light was off. only when i took the car on free way,the light came in.

Certain systems on the car are only tested by the computer(s) at certain times.
The computer has to see certain sets of specific conditions before it can run certain tests.
A period of time at a steady speed can be one of those conditions.
There are many different conditions that have to happen, for many different tests.
So what you saw (freeway drive instead of stop-and-go) can be normal.

Driving habits can prohibit some tests from running, like if you only drive the car one mile at a time, there are certain tests that might never run. There could be failures that never get detected by the computer due to this.






to be very frank,i do not know what is misfire.

mis·fire (ms-fr)intr.v. mis·fired, mis·fir·ing, mis·fires 1. To fail to ignite when expected. Used of an internal-combustion engine.
2. To fail to discharge. Used of a firearm.
3. To fail to achieve an anticipated result: a scheme that misfired.

Also this: http://www.aa1car.com/library/misfire.htm




but can this also cause 420 code?

Misfire? It will not cause the cat code directly.....but--
Misfire can cause DAMAGE to the element inside the cat, if it is severe and ignored. That can lead to the P0420 cat code once the cat is damaged.

A cat can also just be bad, it loses efficiency over time, could be clogged, contaminated, poisoned, carboned up, and a few other things that aren't always common failures for most people.

The P0420 code is for a cat that has lost its efficiency, that is what the computer detected during its testing. That is ALL.
But, there are other possible reasons the computer could falsely detect this, and exhaust leaks are one of them.


and can the spark plug gap or too loose/tight spark plugs cause this?

These can cause misfires. If there were misfires, there should have been codes related to that. They would be P030x, with x being the number of the cylinder in question, or 300 for random misfire. The CEL should also have been flashing angrily while the misfires were happening.


Misfire is not the only thing that can damage a cat. Improper fuel control is a root cause, anything that could cause unburned fuel to escape the engine and go into the cat can hurt it. Think about it: A misfire is uncontrolled fuel that didn't get burned inside the engine, so the cat has to burn it. Anything that causes the engine to run poorly can be a root cause.

I have seen an Odyssey van with about 5% diesel-gas mix not only ruin 3 catalytic converters (or more, since it was at a dealer in another state a day prior), it also ruined the engine. All with only about 10,000 miles on it.

has 420 nothing to do with the transmission fluid,coolant change?

Not in my mind. Not at all.

Unless it got a fuel injector cleaning or injection flush. I have seen this cause misfire, and the possibility of damage due to that could exist. It would be nearly impossible to prove though, if you were to try to blame someone else for it failing.


HTH

 
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thanks ezone for the detailed answer. I am going erase the code as you suggested and will take it from there.
is disconnecting battery for 10-15 min enough or I have to pull the fuse 15A - I read somewhere that 15A has the immobilizer key code stored and if you don't have the original key, your car may not start. I am the second owner and not 100% sure if I have the original key. what is the safest way to reset the engine light?

 
Rep Power: 518

My info says a battery disconnect will clear that code. Or you could take it to DangerZone and have them erase it with their code reader.

I have never heard of the immobilizer issue you speak of on that car (I know of an issue on early 8th gens). I would think there would be lawsuits for every other dead battery if that were the case.

 
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Wait up----how did you GET (read) the code in the first place? That code reader should erase codes.

 
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Did it at Pep boys they do it free here in CA. other guys wanted from $30 to $50 just to read the codes.

 
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not the battery, I was mentioning about removing the fuse. I read somewhere that fuse 15A stores the immobilizer info and if you reset it by pulling it out, it will reset your immobilizer codes and your car may not start.

 
Rep Power: 518

Again, (unless I misunderstand what you are saying) I have not heard of that, and have not witnessed that. I looked in Hondas ISIS info system, and found no reference to what you described.

If you have serious documentation about this that you can link, I'd like to read it.

Now, if you mean just leaving a fuse completely out (or blown). Of course that can disable the car-- if you pull the right fuse(s). Duh.


A fuse alone does not store data.
There are several fuses that protect power for the immobilizer systems various components, and if any are left completely out (or blown), it may keep the car from running because the system isn't completely powered up.
All immobilizer information is stored within the various system components.
It takes a scantool with access to the immobi system to erase or alter that data.

Data for a cloned key is stored within the key itself.

You can google Honda bulletin 01-053 for more info on the type 3 Immobilizer system.

HTH

 
Rep Power: 0

thanks ezone. actually I read http://honda-tech.com/showthread.php?t=2366793
but looks like that's not related to the ECU fuse.

 
Rep Power: 518

Ok, I see....
http://honda-tech.com/showpost.php?p...82&postcount=7
http://honda-tech.com/showpost.php?p...7&postcount=14

PCM was fried because the alternator bolts were left loose.
This is such a common issue, Honda issued service information about it.
I have seen them both burned up and seen a few survive.

And a new PCM has to be programmed before the car will run. Software or immobilizer, no matter, it still has to be programmed.

I'd guess the people in the threads were upset that the info they received came from people that only answer phones or sell parts at the dealerships, not the actual techs that have to do the actual work and have the best chance of having actual answers. (I shouldn't say that too loud, I can't remember every little nuance of every repair. I have to use books sometimes too.)

 
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erased the code by disconnecting the battery. did 10-15 miles of city driving and the light is off as of now.
also completed my second drain-fill of the ATF today.

 
Rep Power: 518

Try another freeway trip.
The same trip that got your light to come on the first time.
Go back home, shut it off, let it sit overnight.

Then make the exact same freeway trip again the next day.

The computer has to see the failure happen two times (in a row?) before it will turn the light on.

If the P0420 returns again, you could try a good hard high speed run on the highway for a while. (IDK how your "freeway driving" is where you are, some places are 95mph all over and some are all traffic jams).

Fuel quality and driving habits can contribute to shortened cat life. Changing those conditions could extend the life of the cat a bit.


Did I mention this?
Word up: http://www.toptiergas.com/
Use quality fuel from a top tier supplier, and use the proper low octane fuel.

HTH

 
Rep Power: 179

According to NGK website there is no v-power plug for your car.

G-Power Platinum
ZFR6FGP
Stock No. 7100
Plug Gap 0.044

Iridium IX
ZFR6FIX-11
Stock No. 6441
Plug Gap 0.044

Laser Series
PZFR6F-11
Stock No. 3271
Plug Gap 0.044

 
Rep Power: 518

If they are ZFR6F-11, (or 5F) I wouldn't see a problem with that.

 
Rep Power: 179

Put back the old plugs and see what happens.

 
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thanks ezone and nsrhonda89.
I took my car today on free way and the light came back
my new plugs are NGK Vpower - ZFR6F-11 and the autozone guy confirmed they fit in my car. also read on this website that these plugs can be used.
putting back the old plugs is not an option cause unfortunately I threw them.

ezone, whats the purpose of driving with high speed after light is comes on,sorry I didn't get that part. can you please elaborate?

should I check the o2 sensor first before changing the cat conv? when I changed the coolant about 2 weeks back, I saw smoke coming from that area. actually after filling new coolant I left the radiator cap opened for about 30 sec to 1 min and started the car causing the car to overheat(and I think so and this is why smoke came)

can I check myself if the o2 sensor is good or bad? is it easy to replace that or i need to take the car to mechanic?
what are your thoughts about this o2 sensor?

http://www.amazon.com/Denso-234-4209...ar=1&carId=001

 
Rep Power: 518

I took my car today on free way and the light came back

I figured that would happen, that's why I said to do it.
Driving in stop and go traffic won't normally allow the cat monitor to run.

my new plugs are NGK Vpower - ZFR6F-11 and the autozone guy confirmed they fit in my car. also read on this website that these plugs can be used.

Correct.
As long as they were installed correctly, they shouldn't be an issue.


ezone, whats the purpose of driving with high speed after light is comes on,sorry I didn't get that part. can you please elaborate?

The thought is to attempt to burn off contaminants with high speed/heavy throttle operation. To get the cat to the upper end of its operating temperature range for an extended period of time, but without really overheating it and causing further damage. When some cars fail an emissions test for a bad cat, there are occasions where a good hard highway run can get the cat to pass a test that it previously failed.

should I check the o2 sensor first before changing the cat conv?

There are a slew of other codes that would address failed O2 sensors. If you don't have any, then you don't need it.




when I changed the coolant about 2 weeks back, I saw smoke coming from that area. actually

What area?
The cat or the radiator?


after filling new coolant I left the radiator cap opened for about 30 sec to 1 min and started the car causing the car to overheat(and I think so and this is why smoke came)

Unpossible.
And this may be a clue.....
What exactly did you see that made you think the engine was overheating in 30 seconds?
You started the car with the radiator cap off, and WHAT HAPPENED??
Percolating? Spewing coolant out? WHAT?

Answer this one ASAP, this kind of leads me to think it could sound like a blown head gasket. But it depends on what really happened.


can I check myself if the o2 sensor is good or bad?

With a scanner, you can watch activity on the datalist. (You won't make heads or tails of it without a lot of experience.)
If there are no codes for any O2 sensor, then most can assume they are fine.

is it easy to replace that or i need to take the car to mechanic?

Anything is easy if you have the right stuff, whether it be knowledge or tools.You would probably need an O2 sensor socket to do the job: http://www.amazon.com/Lisle-12100-Ox...gy_auto_text_b

what are your thoughts about this o2 sensor?

Wow, that's freekin cheap.
Look on your old sensor. It should have the manufacturers name and their part numbers stamped into the body of it.
Denso and NTK are OE suppliers to Honda, so if you can pick out the right version, it should be ok. But there are no guarantees that aftermarket parts will be correct for your application, and certainly not over the interweb.

Did you happen to notice this little disclaimer on that page: "This product is in a Denso package, however the part may have been manufactured by an independent Denso supplier."

BUT I sure wouldn't be throwing sensors at it, it would get a cat for the P0420 code.But if it has a blown head gasket......now there are more issues to contend with.

HTH

 
Rep Power: 0

Thanks ezone.

Attached the image where I saw the smoke, sorry I didn't realize this isn't the O2 sensor, after reading more I realize that its not under the hood but near the cat which can be seen only from underneath the car

after filling new coolant I left the radiator cap opened for about 30 sec to 1 min and started the car causing the car to overheat(and I think so and this is why smoke came)

Unpossible.
And this may be a clue.....
What exactly did you see that made you think the engine was overheating in 30 seconds?
You started the car with the radiator cap off, and WHAT HAPPENED??
Percolating? Spewing coolant out? WHAT?


1)smoke started coming from the part i shown in the picture(it was like smoke you see when hold cigarette in hand)
2)the dashboard temperature gauge went to max(red)


while taking below picture,I just open the radiator reservoir and it was filled till neck. this is not the first time i opened the reservoir after changing coolant, but it was always leveled till max mark.
i am not too sure if this is normal or a problem.

 
Rep Power: 518

Ok, the part circled in your pic is the first O2 sensor, which hasn't been proven that is needed.
You can see the wiring for the rear O2 sensor in the pic. The cat is between those 2 sensors. Your cat is NOT under the car.
The whole area gets HOT, so anything spilled or dropped can make smoke.


You managed to sneak a reply into the quoted and shaded area above this section, that was sneaky. Wanna answer this one now?



If you have repeatedly found the reservoir is full or overflowed, and the radiator is now low (not completely full to the top), this is a common symptom of a blown head gasket. You probably have bigger problems now.

 
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I see what you are saying...
http://wiki.answers.com/Q/What_are_t...wn_head_gasket

so I might have multiple problems i) cat ii)head gasket ?
what are the implications of the blown head gasket?

overheating was observed only once during the coolant change. its is no more a problem. I drove the car up to 1.30Hr nonstop and the the temperature gauge was always in the middle. also, i didnt see any difference in the driving conditions.

 
Rep Power: 518

damn. I can't read.

 
Rep Power: 518

Implications of a blown head gasket:
Coolant loss and continued overheating.....
If it gets hot enough, you start ruining large engine parts.
At that point, you are without wheels.
You need large amounts of cash.
First the cylinder head, then the rings, then you melt aluminum and replace an engine. And the radiator, and hoses, and other stuff.


I apply shop air pressure to each cylinder to
A)prove there is a problem, and
B)show exactly which cylinders(s) are affected.
The method has not failed me yet.
The combustion leak detector that you can get at the parts stores don't always show proof of the problem.

 
Rep Power: 0

thank you ezone,
some of the most common symptoms according to many forums of the blown head gasket are:
1)white smoke from the tail - not observed
2)coolant smell if heat is full inside the car - not observed
3)signs of coolant in the engine oil - visual inspection of the dipstick didn't show any signs
4)spark plugs showing signs of the presence of the coolant - opened sparkplugs - no signs
5)opened the radiator cap and start the car. bubbles will come out of the radiator - Positive. saw one bubble at a time coming out.

today I flushed the coolant and after measuring the quantity, it was aprox half gallon(half of what I put in 2 weeks back)
1)does this mean that some coolant burned inside the radiator and some moved inside the reservoir? also, coolant is not getting circulated?
2)does this also means that the radiator cap is the problem and not the head gasket?

 
Rep Power: 518

5)opened the radiator cap and start the car. bubbles will come out of the radiator - Positive. saw one bubble at a time coming out.

This is the usual way it fails on this engine.

I take it a few steps further for testing and verification, as I may have described earlier, because I have to know WHICH cylinder has the breach so it can be closely inspected upon teardown.



today I flushed the coolant and after measuring the quantity, it was aprox half gallon(half of what I put in 2 weeks back)

Draining the radiator only nets you about half of the total coolant capacity.

Not sure what you are getting at, but it matters not... You may have noticed the coolant was not completely full in the radiator when you removed the cap. The missing coolant usually got pushed into the overflow reservoir, and can't be pulled back in to the radiator. The reservoir is either completely full or it has been overfull and excess coolant got pushed all of the way out.

Depending on the severity of the head gasket leak, it may take some time and miles for all this to happen.



1)does this mean that some coolant burned inside the radiator and some moved inside the reservoir? also, coolant is not getting circulated?

No, it just gets displaced by the leaking combustion gases and pushed into the overflow reservoir. Since there is now an "air bubble" in the radiator, it can't pull the coolant back in from the reservoir.


2)does this also means that the radiator cap is the problem and not the head gasket?

The cap is not the usual failure, unless there is steam erosion in the radiator neck where the rubber gaskets of the cap have to seal (would need a radiator if this happened). This is easy to see and feel once you figure out what you are looking for. It doesn't happen unless there was a severe overheat event that boiled the coolant.
This is all usually collateral damage, not the cause of damage (most cases).
The cap is easy to test with a pressure tester, and cheap enough to just replace for the heck of it.


HTH

 
Rep Power: 0

sorry I disappeared for couple of days, but thanks ezone for your help.

 
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Replaced Radiator cap and looks like that worked. I saw a small leak at the end of reservoir where the tube connects. Looks like previous owner used a metal wire to tighten the tube with the reservoir and that cracker the tube and it was leaking coolant (very small qyt though).I also overfilled the radiator with the coolant after I drained the radiator and looks like that put more pressure on the tube which was already cracked.
Now after opening the radiator every morning before starting the car, I can see its full and reservoir has coolant level in min and max level.
the car is not overheating and temperature gauge is always in the middle of H and L. So I guess I am saved from the blown head gasket repair for this time
Also, I noticed that my ATF level was too high(I changed ATF couple of weeks back) so I drained some to correct the level. I haven't taken my car on the freeway since disconnecting the battery and draining some ATF so don't know if the engine light will come back again.
Are these two anyways linked(ATF overfilled and P0420)?

 
Rep Power: 518

Absolutely not.